* It is duplicated with `dim_`. We can use `dim_` to calculate `numel`
  everytime. It does not cost too much.
* `numel` is not initialized by constructor. Also, `numel` is hard to
  synchronize with `dim_`.

So just remove it.

Add `BlockDesc` and `ProgramDesc` to framework.proto

Fix linking error on mac.

Bug fix for get device_context in conv2d op.

Implement activation related operators

Add rank loss operator

Add crop op

Add clip op

add the transpose op

Convolution operator

* remove alias

"add name convention url"

Add program.md

move OpProtoAndCheckerMaker from operator to op_proto_maker

Add StridedCopy method

some addition for mkldnn_act