fix #152

add ce for ERNIE

add ce for BERT

add check_cuda for ERNIE

Add cuda check for bert

[NOT MERGE]Support multi process training for BERT

modify elmo README.md

 fix pyreader return empty array as None in paddle 1.5

fix #151
paddle 1.4 does not occur this problem

update bidaf link

fix #138

* added a train file for ngraph

* updte train.py instead

Add the difination epoch_id before its reference

Delete the code (import ipdb)

fix typo

fix for py3

add windows pe note