Add nccl to docker image

fix clang build error

add book02.recognize_digits mlp train test

* Init file

* Update

* Update

* Complete conv net of MNIST

add mkldnn branch tests for pool and fc

Change the name of the export.map to paddle_capi.map which need to be…

* Adding incremnt op

* Fixing comment about step attribute

* Adding the interface for the momentum optimizer
* Adding a comment about accumulators

Split paddle_capi_whole into paddle_nn_engine and paddle_layers two s…

* Unify `set_feed_variable` to one method

* Move global scope to python, not in C++

* add test_fit_a_line

* Update

* fix persistable bug

* fix elementwise add bug

* set correct attr for bias op in fc layer

* set correct attr for bias op in fc layer

* Update

1. Add init_program to hold initializers
2. bug fix

* add test_fit_a_line

* fix persistable bug

* fix elementwise add bug

* fix type

* add gitignore

* Complete fit_a_line test

* revert code

* Clean up

* Revert "revert code"

This reverts commit eb1aa015.

* Refine

* Fix unit test

fix elementwise add bug

* Delete kid

* Delete local scope

* Remove template parameter for Tensor methods

* Also check the type is correct when data()
* Simplize holder_

* Fix accuracy_op

* Register Code

* Init

* unify layer names

* Update

* Add pool2d layer

* Test recognize_digits_conv

* Clean up