* open dygraph op test, test=develop
* modify to_variable, test=develop
* modify input and output for dygraph, test=develop
* modify input and output for dygraph(fix bug), test=develop
* fix input processing of dygraph op test, test=develop
* fix bug, test=develop
* fix op test, test=develop
* fix forward bug for dygraph, test=develop
* fix mkldnn op test for forward, test=develop
* update nn.py for dygraph, test=develop
* fix crop_tensor_op, test=develop
* fix elementwise_mul_op, test=develop
* fix fill_op, test=develop
* fix some mkldnn op, test=develop
* open backward op test for dygraph, test=develop
* delete log, test=develop
* close backward op test for dygraph, test=develop
* fix bug for edit_distance_op and test_lstm_cudnn_op, test=develop
* fix optest backward bug for dygraph, test=develop
* fix optest backward bug for dygraph, test=develop
* close backward op test for dygraph, test=develop
* close backward op test for dygraph, test=develop
* open dygraph op test, test=develop
* fix op test for dygraph, fix GradOpDescMaker, test=develop
* fix bug for linear_chain_crf_op.h, test=develop
* remove log, test=develop
* remove log, test=develop
* remove log for op_test.py, test=develop
* remove log for op_test.py, test=develop
* fix bug for var_conv_2d_op, change PADDLE_ENFORCE, test=develop
* fix PADDLE_ENFORCE_EQ for hierarchical_sigmoid_op.cc, test=develop
* fix bug for test_increment_ngraph_op.py, test=develop
* fix lod for op test in dygraph, test=develop
* refactor op_test.py to reduce redundant code, test=develop
* fix lod optest, modify InputVar/OutputVar to HasInput/HasOutput, test=develop
* remove debug log, test=develop
* remove redundant code in base.py, test=develop
* fix some error in optest, test=develop
* fix ClearNoNeedBufferInputs function's bug for LoDTensor, test=develop
* refactor op_test.py, test=develop
* remove redundant writing, test=develop
* fix error(get tensor of the grad variable), test=develop
* fix test_concat_mkldnn test_conv2d_mkldnn, test=develop
* fix optest.py for get tensor of LoDTensor, test=develop
* fix optest.py for get tensor of LoDTensor, test=develop
* fix optest.py for get tensor of LoDTensor, test=develop
* fix some redundant code, test=develop
* reslove conflict and rewrite paddle error message, test=develop