Update sentence_sim.md

 add unitest, config, fix ernie_gen bugs and add ernie_tiny_couplet (P…

…addlePaddle#782)

Update release.md

modify_readme_contents,test=develop (PaddlePaddle#480)

update cmd_intro doc (hub download) (PaddlePaddle#453)

update cmd_intro doc (hub download)

Update autofinetune.md

Update autofinetune.md

Merge pull request PaddlePaddle#358 from ShenYuhan/serving_ma

turn i_img on

Create cache directory automaticly

add release note(1.5.0) (PaddlePaddle#332)

* add release note(1.5.0)

* update docs

* update docs

* underline Bert Service for v1.5.0