multi-thread handlerequest

add checkpoint util class and implement

Add groups for conv transpose ops

* wip integrate benchmark scripts

* testing nlp models

* k8s script to start dist benchmark job

* update script

* done support all models

* add README.md

* update by comment

* clean up

* follow comments

expose random_data_generator

Add Inference doc for fluid

Add api docs for RMSProp and modelAverage

send use pinned memory

Add the demo of subgraph splitter

fix dist test

* Enhance reduce op for multi dims.

* Uncomment some unitest.

* Uncomment unitest.

* Remove unused code.

* Fix infershape and python wrapper.

* Add more examples.

* Fix l2_normalize.

* Fix normalization_wrapper.

* Polish code.
1. Rename unitest function.
2. Rename const variable.

Revert "update bcebos url so that it can also be downloaded in inner network"

* Add dice loss.

* Fix comments.

* Remove unused code.

Force some unittests serial

update bcebos url so that it can also be downloaded in inner network