* fix se_resnet model for Optimizer and Linear upgrade, test=develop

* polish code style for se_resnet, test=develop

* using new load api

* merge

* add dygraph user guide in models/dygraph

* remove useless files

* Update mnist_dygraph.py

fix bug

* add muti card support for se_resnext

* add some description to readme.md

* fix typo

* fix reademe

* fix init_path for test

* add se_resnext for dygraph