Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into feature/combine_open_files_and_double_buffer

fix _clone_variable in optimizer.py

Delete overview.rst from api index

hide more apis

Update build script

 move contrib/inference to paddle/fluid/inference/api

fix set-e exit when checking api

* test

* test

* test2

* wip

* test using pr id

* test

* add log

* add log

* test

* test

* test

* test

* add approver check

* revert travis ci

* merge latest api.spec

* fix get token

* update API.spec

* up to date

MKLDNN sum fix: remove in_place condition in loop with memory primitives

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into feature/combine_open_files_and_double_buffer

hide monkey_patch_variable

* fix build doc

* add some description about Python ABI

Fix bugs in the resize_short and simple_transform funciton

* remove block api

* remove clone_variable

* hide block inner apis

* update

* fix tests

The resize_short function used the cv2.resize function in a wrong way.
The simple_transform function repeated the code uncorrectly.

fix pserver with condition block