polish release doc

* add ignore index

* update api.spec

* enhance softmax_with_cross_entropy

refine Analysis test 

Fix cudnn holder bug

program and tensor versioning support

fix fluid benchmark script

Enable conv and batch norm by default

reset received vars on pserver

* Implement norm_op by CUDA instead of Eigen.
* Remove the commented code.

* slightly restructure the document [skip ci]

* Update dynamic_graph.md

add analysis unit test of lac and ner 

* support test using executor without reader

* run imgnet

* update fluid benchmark

* wip

* update

* update all models

* support pyreader

* update

* clean up

* make profile batches contollable

* update API.spec

* update scripts

* clean dockerfile

* update

* clean comments

* add scope argument docstring

* use num_trainers to determine nccl init comms

refine anakin related codes