Release/0.11.0

Fix compile error in android.

Update release note v0.11.0

add v0.11.0 release note

Remove DeviceContext::Finish

refine the gen_docs in build.sh

Release/0.11.0

Refine the doc of layers.py

Fix v2_API equation for img_pool and maxout format.

Change release version

* Fix bug in MergeModel.cpp.

* Add a c-api inferface to initilize the thread environment of Paddle and add a GPU example.

* Add some note for paddle_init_thread and move the inplementation of paddle_error_string into a .cpp file.

* Add some comments.

* init decoder_trainer

* can run

* fix lod

* add sharelod to cross_entropy_grad_op

* add avg_cost to fetch list

* modify learning rate

* can run

* optimie code

* add early exit

* fix print

* revert test_understand_sentiment_conv.py

* add act to fc

add print_operators_doc in travis ci

message cxx compiler version

* fix gpu memory allocation policy

* refine codes

* fix code style

* follow comments

add script to check the cpu env

add softsign into doc.

add graph in IntelOptimizedReadme