* remove net op and cond_op

* fix cpplint

* fix dependency

* delete backward_test; fix compile

* disable batch_norm backward

* rm test_net.py

* make batchnorm test independent of backward.cc

* make test_layer_norm_op independent of backward.cc

* make test_layer_norm_op independent of backward.cc

* delete unused code

* clean up

* Support testing during training by ParallelExecutor.

* Add unit test.

* Improve the interface.

* Follow comments.

Fix debuger bugs

* initial commit

* fix error

* fix typo and order