modify_readme,test=develop

enable gc for predict_classify

add classify inference using infer_program

fix #207

add ce  for ELMo

update

add import random

fix #200

fix a typo

add predict_classifier.py

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