revert 03 image classification: fluid.layers.data->fluid.data

* Revert "change -1 to None in data's shape (#819)"

This reverts commit 77fe59e5.

* Revert "Upgrade API using paddle 1.6 (#813)"

This reverts commit 900ba733.

This reverts commit db3cdc05.

This reverts commit adcdb7b8.

This reverts commit 104c4078.

* change layers.data to fluid.data
* change layers.embedding to fluid.embedding

* fix typo:Infererence

* fix data api

* Modify the formula of lstm

* Update README.cn.md

* Update README.cn.md

* Unify 1.6 api in 06.understand_sentiment

* fix a bug in README.md

* Update README.cn.md

* Modify the formula of lstm

Fixed issue with train_dyn_rnn.py training report nan

update coding_guideline

* fix reader

* update readme

Modified the bug in understand_sentiment
icafe : http://newicafe.baidu.com/issue/76263402/show?cid=5&spaceId=23205&from=email&noticeStatistics=23969354

fix : http://newicafe.baidu.com:80/issue/DLTP-1929/show?from=page， fix book code is not compatible with python3

Modify the code to support python3: fix problem in book05 doc and code

fix link and some mistake in 01.fit_a_line and 09.gan

* modified reademe

Modify the location of test_program definition

mv import __future to begging of file 

use numpy.asarray as data initializer

* replace book url

* replace develop to 1.5

* fix wrong url

* test=develop

* merge

* recrurent to recurrent

* test=develop

* merge

* recrurent to recurrent