Wrap unsqueeze & squeeze ops

* Enhance the function of fused_elementwise_activation_op

* enhance unit test

* Clean Code And Add Doc

* Add compound functors

* Fix doc and enhance unit test

* define Dx and Dy for d_binary_func

* add mul_scale

* add mul_scale

* add elementwise_mul

* code refine

* code refine

* add doc

* add  AsIntermediate

* add test for dist and memopt

* update transformer too

add python api for sampling_id op

fix graph_to_program_test to be platform-independent

* fix dist transpile with memopt

* update api.spec

* polish dist transpile api

* update apispec

* update apispec

update anakin commit id due to fix 5117 compile bug

* Add proposals generation operator for Faster-RCNN.

add fusion gru 

small fix of op_desc

refine seq2batch

graph to program pass

* Polish PrintOp

* Polish PrintOp

* Polish PrintOp

* Refine test_print_op

* enhance pad_constant_like_op

* add API

* add API

* Improve fake_dequantize_op.
* Follow comments.

* add ScaleOpVarTypeInference for scale op

* scale op support scale selected rows

* optimize code

* use FindVar

* use FindVarRecursive in ScaleOpVarTypeInference

Sequence pad op

* refine dist train RPC deps

* clean up

* clean up

* fix ut

* remove input for fetch_barrier

* follow comments

Add concat op converter

* test fix release branch api check

* fix reviews > 30

* check approval after test, check api diff before test

Add unstack op

Enforce requested size of tensor to be sufficiently large

Reusing primitives for forward Batch Norm operator

Fix random diff between python2 and python3