Enable automatic shape inference when using Lambda layers and CNTK. Also fixed the test_no_grad that was catching ValueErrors that had nothing to do with not having a gradient. (#10647)

### Summary
`normalize_data_format` was being called twice in `_Pooling2D`

### Related Issues

### PR Overview

- [n] This PR requires new unit tests [y/n] (make sure tests are included)
- [n] This PR requires to update the documentation [y/n] (make sure the docs are up-to-date)
- [y] This PR is backwards compatible [y/n]
- [n] This PR changes the current API [y/n] (all API changes need to be approved by fchollet)

### Summary
This PR adds the missing examples to the list of examples in _examples/README.md_.

### PR Overview

- [n] This PR requires new unit tests [y/n] (make sure tests are included)
- [n] This PR requires to update the documentation [y/n] (make sure the docs are up-to-date)
- [y] This PR is backwards compatible [y/n]
- [n] This PR changes the current API [y/n] (all API changes need to be approved by fchollet)

`keras.regularizers.l1_l2()` takes two arguments. The doc was misleading.

In light of SuperConvergence [1], the user might want to increase the learning rate during training so saying 'reducing' is no longer appropriate.
[1]: https://arxiv.org/abs/1708.07120

* Apply mean and stddev to cntk backend's random_normal

* Update backend_test.py

Add test case for non-standard normal distribution parameters

* Make binomial, uniform, and normal random variables vary and add tests

* Fix formatting issues

* Reuse validation enqueuer

* Fix CI

* Indent val_data correctly

* Typo

* Add pr template

* Make uppercase to be consistent

* Change according to review

* Remove unused relu6

* Remove doc for loading relu6

* DOC: Fix IMDB get_word_index documentation

* DOC: Fix reuters get_word_index documentation

* Doc

* Fix indent

* Fix Dense layer bias_add bug when ndim > 2.

* Address comment

* Add saving tests

* Add regexps to verify that the expected error is being raised

* ignore empty KERAS_BACKEND environment variable, refs #10516

* fixed spacing (PEP8), refs #10516

Changed border_mode='same' to padding='same' in the example to match it with the parameters of Conv2D.

* Add output shape argument to transposed conv. to resolve ambiguity

* Remove deconv2d  legacy preprocessor

* Add unit tests for output shape in 2d/3d transpose

* Replace output_shape with output_padding

* Update docstrings

* deconv_length handles output_padding=None

* Unit tests

* Check if stride is greater than output padding

* Pull request revision

commit 65670e69dcb9249f3c7d520167d2701edfa31986
Author: David Silva <davidtvs10@gmail.com>
Date:   Tue Jun 19 06:00:55 2018 +0100

    Replace two spaces by br tag to force new line

commit d7141937317634af23b602de63363d06e96804a8
Author: David Silva <davidtvs10@gmail.com>
Date:   Tue Jun 19 05:26:57 2018 +0100

    Add output shape equation to docstrings

commit 5f06a7879bd5679eb290e379b73ff68d5cfceda1
Author: David Silva <davidtvs10@gmail.com>
Date:   Sat Jun 16 17:26:20 2018 +0100

    Fixes following @fchollet revision

commit b4530ae775ec67b79db801b1e2a514a83ba980cc
Merge: 6b99d23 5fcd832b
Author: David Silva <davidtvs10@gmail.com>
Date:   Sat Jun 16 16:17:41 2018 +0100

    Merge remote-tracking branch 'upstream/master' into trans_out_pad_dev

commit 5fcd832b
Author: Pavithra Vijay <psv@google.com>
Date:   Fri Jun 15 16:29:32 2018 -0700

    Fix small doc error (#10453)

commit 2ec486ba
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Fri Jun 15 14:07:28 2018 -0700

    Model input validation fix.

commit ffa99d69
Author: Pavithra Vijay <psv@google.com>
Date:   Fri Jun 15 13:52:14 2018 -0700

    Fix use_bias in some convolutional layers (#10444)

    * Fix use_bias in some convolutional layers

    * Fix Conv2DTranspose test

commit 6aace305
Author: ebatuhankaynak <ebatuhankaynak@users.noreply.github.com>
Date:   Fri Jun 15 22:00:24 2018 +0300

    Update convolutional.py (#10452)

    Changed
    "# now model.output_shape == (None, 20, 16. 64)"
    to
    "# now model.output_shape == (None, 20, 16, 64)"

    (There is a dot instead of comma).

commit 2d183db0
Author: Sachin Abeywardana <sachinruk@users.noreply.github.com>
Date:   Fri Jun 15 04:19:45 2018 +1000

    corrected batch norm implementation in cntk (#10427)

commit 52f608cb
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Thu Jun 14 05:44:22 2018 +0900

    Add tests for inputs set dynamically (#10416)

commit a68c516e
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Thu Jun 14 03:43:43 2018 +0900

    Update a CNTK version on Travis (#10419)

commit 4f90f95f
Author: ebatuhankaynak <ebatuhankaynak@users.noreply.github.com>
Date:   Wed Jun 13 21:39:47 2018 +0300

    Update faq.md (#10422)

    Changed "Notes that the methods...." to "Note that the methods"

commit 8e5b8533
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Thu Jun 14 03:39:13 2018 +0900

    Move `get_source_inputs` (#10415)

commit a40f3355
Author: Max Pumperla <max.pumperla@googlemail.com>
Date:   Wed Jun 13 20:36:50 2018 +0200

    [docs] more details for adagrad/delta, clarifying usage of rho (#10410)

    * some more meat for ada docs

    * incorporate suggestions

    * line breaks

commit 29a22a8d
Author: fuzzythecat <fuzzy0427@gmail.com>
Date:   Wed Jun 13 02:57:38 2018 +0900

    Add missing named arguments in ImageDataGenerator in examples (#10389)

commit 0237542f
Author: EyeBool <diataha.personal@gmail.com>
Date:   Mon Jun 11 09:44:02 2018 -0700

    Fixed a type: repeated 'in common'. (#10394)

commit 3eab6103
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Thu Jun 7 16:09:58 2018 -0700

    Preserve input shape data when serializing deferred-build Sequential models.

commit db849f8e
Author: jlopezpena <jlopezpena@users.noreply.github.com>
Date:   Thu Jun 7 19:54:51 2018 +0100

    Doc update (#10376)

    A couple of variables are "used" in two examples without being defined. For consistency with other examples where auxiliary dimensions are defined, I think it would be better to explicitly assign them a value. I just used made up values, feel free to change to whatever makes more sense!

commit 67e242d9
Author: Max Pumperla <max.pumperla@googlemail.com>
Date:   Thu Jun 7 20:54:23 2018 +0200

    Add spatial dropout and 3D global pooling to docs (#10373)

    * spatial dropout in docs

    * 3d global pooling in docs

commit 4e829712
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Wed Jun 6 16:17:29 2018 -0700

    Update docs for 2.2.0.

commit 632560d9
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Wed Jun 6 11:53:18 2018 -0700

    Style fix

commit bbf42834
Author: Bohumír Zámečník <bohumir.zamecnik@gmail.com>
Date:   Wed Jun 6 20:52:26 2018 +0200

    CuDNN RNN layers nested in TimeDistributed are not converted when loading (#10357)

    * Add a unit test for CuDNNGRU conversion with TimeDistributed.

    * Extract duplicated function convert_model() to _convert_model_weights().

    * #10356 Convert weights of CuDNN/plain RNN nested in TimeDistributed.

    Same case as for Bidirectional, except that in TimeDistributed there's only
    one nested layer instead of two.

commit 13548e8b
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Thu Jun 7 03:51:37 2018 +0900

    Add tests for inputs set dynamically (#10367)

commit 56b255cc
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Wed Jun 6 10:51:06 2018 -0700

    Update to Keras Applications 1.0.2 (fixes NASNet issue).

commit 513f7b1b
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Thu Jun 7 00:47:37 2018 +0900

    Fix a version number (#10361)

commit 9a58f7b2
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Tue Jun 5 17:40:44 2018 -0700

    Prepare 2.2.0 release.

commit 3f4ccbb1
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Tue Jun 5 17:30:48 2018 -0700

    Add error message when calling `summary` on unbuilt subclassed models.

commit 25d0193e
Author: tiferet <tgazit@gmail.com>
Date:   Tue Jun 5 21:23:27 2018 +0300

    Supporting channels_first data format with crossentropy losses (#9715)

commit 1e80c1a2
Author: KuzMenachem <35711942+KuzMenachem@users.noreply.github.com>
Date:   Tue Jun 5 20:10:43 2018 +0200

     Fix HDF5Matrix issue when working in conjunction with TimeSeriesGenerator (#10334)

    * Fix issue when working in conjunction with TimeSeriesGenerator

    The TimeSeriesGenerator class uses xrange through six which caused an IndexError

    * Add test

    * Add corresponding test

    * Fix for python3

    * Simplified code

    * Fix indent

    * Fix test

commit ce56322a
Author: David Schwertfeger <david.schwertfeger@googlemail.com>
Date:   Tue Jun 5 00:15:25 2018 +0200

    FIX: Tensorboard callback only supports logging Embeddings layer weights (#7766)

    * Embed layer-outputs rather than layer-weights in TensorBoard callback

    * Update docstring and allow multiple inputs

    * Fix tests

    * Renaming

    * Set learning phase

    * Compute embeddings in batches

    * Pass embedding data explicitly

    * Actually process embeddings in batches

    * Allow multiple inputs and validate input data

    * Add example

    * Delete utils.py

    * Revert uncorrectly resolved merge-conflict

    * Minor renaming

    * Add comment clarifying the design choice

commit b2176482
Author: Tommi Koivisto <tkoivisto@users.noreply.github.com>
Date:   Mon Jun 4 20:26:41 2018 +0300

    Add an advanced activation layer for ReLU (#10322)

    The max_value argument can not be used in a layer, except
    custom layer or Lambda. Hence, similarly to LeakyReLU or
    for example Softmax, this PR adds a layer for ReLU,
    enabling also a capped ReLU to be used.

commit 1365ed5d
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Tue Jun 5 02:07:23 2018 +0900

    Reduce tests for applications (#10346)

    * Reduce tests for applications

    * Make selection over all models random

commit 52e3f983
Author: Anirudh Swaminathan <aniswami97@gmail.com>
Date:   Sun Jun 3 01:22:09 2018 +0800

    Improve the docstring of Conv3DTranspose (#10342)

    * Add depth as third dimension in docstring of
      Conv3DTranspose in convolutional.py in keras.layers

commit f89b3397
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Sun Jun 3 02:21:06 2018 +0900

    Move tests for applications (#10341)

commit c9cb6087
Author: François Chollet <francois.chollet@gmail.com>
Date:   Fri Jun 1 23:53:49 2018 -0700

    Split `applications` and `preprocessing` modules. (#10339)

    * Split `applications` and `preprocessing` modules.

    * Fix dependencies.

commit a3664246
Author: Zhengping Che <Peterche1990@Hotmail.com>
Date:   Sat Jun 2 07:13:24 2018 +0800

    Handle `mask` in `TimeDistributed` wrapper. (#10242)

    * equip TimeDistributed with mask and unspecified input length

    * fix bugs in theano. add test on timedistributed + masking

    * skip tests on cntk with multiple unspecified time lengths.

    * move static shape inference to theano_backend, add docstring, etc.

    * fix format

commit 7365a99f
Author: fuzzythecat <fuzzy0427@gmail.com>
Date:   Fri Jun 1 04:45:26 2018 +0900

    Fix doc (#10327)

    Fixed doc

commit fe066966
Author: fuzzythecat <fuzzy0427@gmail.com>
Date:   Wed May 30 13:49:44 2018 +0900

    Add pooling options in MobileNetV2 (#10313)

    * Add pooling option

    * Add pooling test

commit 315a80ae
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Wed May 30 01:43:37 2018 +0900

    Improve docstrings of applications (#10310)

commit 25283eac
Author: Francois Chollet <francois.chollet@gmail.com>
Date:   Tue May 29 09:31:14 2018 -0700

    Fix typo

commit 0de2adf0
Author: fuzzythecat <fuzzy0427@gmail.com>
Date:   Tue May 29 13:58:18 2018 +0900

    Fix doc  (#10308)

    * Fix naming convention

    * Add missing doc

commit 9bff5b1a
Author: r-kellerm <34206121+r-kellerm@users.noreply.github.com>
Date:   Mon May 28 03:45:35 2018 +0300

    Typo fix (#10293)

commit 794f8143
Author: Botty Dimanov <bottydim@users.noreply.github.com>
Date:   Fri May 25 22:21:41 2018 +0100

    Handle capitalised extensions in list_pictures (#10220)

    #10219

commit 84aa7b5f
Author: Wang, Zhiming <zhiming.wang@intel.com>
Date:   Sat May 26 05:20:57 2018 +0800

    Non training Batch Norm operator has bad performance for it running into tensorflow's non fused batch norm API (#10207)

    * When use tensorflow as backend, let batch norm run into fused batch norm as much as possible, which has better performance.

    fix issue: http://github.com/keras-team/keras/issues/10058

    * In Tensorflow backend, let batch norm call to FusedBatchNorm only NHWC format, also gamma and beta are not None.

    Test result:
    test env: with Tensorflow(commit a543d9471047ca3f6881c87105fcbe2cdff9207d Date:   Thu May 10 17:43:30 2018, local build), python3.4, centos7.4
    test cases:
      "pytest  ./tests/keras/layers/normalization_test.py"  <all passed>
      "pytest  ./tests"      <keep same result as without this commit's modification on BN>

    * fix code sytle.

    * 1. Add axis parameter in backend's batch_normalization functions.
    2. Refine the batch_normalization function in tensorflow backend, Let's it call to fused batch norm as much as possible.

    Thanks the coments from fchollet.

    * Trigger

    * 1. add default value -1 for parameter axis in batch_normalization function in backend.
    2. fix some code style.
    Thanks the comments from fchollet.

commit e6d21795
Author: Stanley Bileschi <bileschi@google.com>
Date:   Fri May 25 17:19:38 2018 -0400

    Adds to and alphabetizes documentation of Layer base class. (#10282)

    * Alphabetizes and adds to layers doc.

    * Responding to @cais comments

    * fix spacing.  Remove in(out)bound_nodes

commit 5eecd55a
Author: Amir Alavi <s.amir.alavi@gmail.com>
Date:   Thu May 24 16:54:20 2018 -0400

    load_weights will fail if shape mismatch (#10266)

    Fix for #10265

commit d476ecc7
Author: jnphilipp <mail@jnphilipp.org>
Date:   Thu May 24 19:52:11 2018 +0200

    Use count_params function for non_trainable_count. (#10280)

commit a07d9f3f
Author: Stefano Cappellini <contact@stefanocappellini.com>
Date:   Thu May 24 19:50:21 2018 +0200

    Fixes automatic doc generation problem with nested lists. Adds a new test (#10212)

    * Fixes automatic doc generation problem with indented lists. Adds a new test

    * Some style fixes on doc automatic generation files

    * Fixes a bad space in convolutional_recurrent.py

    * Changes the test_doc_auto_generation in order to include a doc string taken from the codebase. Allows text lines following nested lists

commit 5a48df22
Author: Clemens Tolboom <clemens@build2be.com>
Date:   Thu May 24 00:00:42 2018 +0200

    Make Dot documentation inline with Concatenate (#10271)

    Doc expects a list containing 2 tensors.

commit 20644772
Author: askskro <ak@aiascience.com>
Date:   Wed May 23 23:59:58 2018 +0200

    Typo in docstring for softplus (#10277)

    Softplus docstring missing a parenthesis.

commit c77267af
Author: Brian Nemsick <brian.nemsick@gmail.com>
Date:   Wed May 23 11:54:36 2018 -0700

    Remove deprecated model.model from engine/saving (#10275)

commit 08c87366
Author: vkk800 <vkk800@users.noreply.github.com>
Date:   Tue May 22 23:03:51 2018 +0200

    Refactor ImageDataGenerator (#10130)

    * Create get_random_transform and refactor

    * Fix style and add tests

    * Add more tests

    * Fix documentation error

    * Fix documentation style issue

    * add apply_affine_transform

    * document transformation dictionary

    * Doc style fix

commit 25a8973d
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Wed May 23 04:18:46 2018 +0900

    Increase test coverages by factorizing CNTK pads (#10259)

commit abd02940
Author: brge17 <33430930+brge17@users.noreply.github.com>
Date:   Mon May 21 18:42:07 2018 -0700

    Remove Sequential.model deprecation warning (#10256)

    * Remove Sequential.model deprecation warning

    * Remove dead line of code

commit 2eed2a5d
Author: Taehoon Lee <me@taehoonlee.com>
Date:   Tue May 22 03:11:43 2018 +0900

    Increase test coverages by adding invalid CNTK usecases (#10236)

* Revert "Pull request revision"

This reverts commit fb7c367a1560f89d9940e32962d2b3807a54ce08.

* Pull request revision (v2)

* Replace HTML markup by markdown

* autogen classes and functions

* remove unused, regex strings, simpler ###

* parantheses, not backslash

* fix signature

* fix for tf backends

* Map TensorFlow tensor with dtype=tf.string to NumPy dtype='object', fixes #10459

* Replace _numpy_type(tensor) method with tf.as_dtype(tensor.dtype).as_numpy_dtype

* Fix use_bias in some convolutional layers

* Fix Conv2DTranspose test

Changed 
"# now model.output_shape == (None, 20, 16. 64)" 
to 
"# now model.output_shape == (None, 20, 16, 64)"

(There is a dot instead of comma).

Changed "Notes that the methods...." to "Note that the methods"

* some more meat for ada docs

* incorporate suggestions

* line breaks