* fix warnings

test=develop

* fix enforce test

test=develop

* Add check of input in sequence_expand op.
test=develop

* Correct the unittest of sequence_expand op.
test=develop

* wip simplify operator framework

* wip

* wip

* done test=develop

* clean test=develop

* fix test=develop

* fix deps test=develop

* fix cpu build test=develop

* fix tensorrt build test=develop

* fix tests test=develop

* fix test=develop

* fix cpu build test=develop

Do not use ctor

* Reduce line of codes.
* We can use virtual function for Maker now.
* The implementation does not care what maker holds, it is easier to
refactor later.

* script to add semicolon

* fix typo

* Move framework.proto to proto namespace

* Fix compile

* Fix compile

* Fix Compile

There are mainly following fixes:

- take `DeviceContext` as the template parameter of math functors and OpKernel instead of `Place`
- remove `eigen_device` interface in base class  `DeviceContext`
- remove `GetEigenDevice` interface in `ExecutionContext` and base class `DeviceContext`
- remove unused `platform::EigenDeviceConverter`
- rename `REGISTER_OP_GPU_KERNEL` to `REGISTER_OP_CUDA_KERNEL`
- rename `USE_GPU_ONLY_OP` to `USE_CUDA_ONLY_OP`

* Adding documentation for seq_expand

* Adding documentation for seq_concat_op

* Adding documentation for sequence_conv

* Adding sequence_pool

* Fixing review comment

* Adding sequence_softmax

* Updating doc for sigmoid_cross_entropy_with_logits

2. Fix comments and paddle enforce check

1. Add more comments and exmples
2. Rename repeat_lod to expand_lod
3. Remove unused head file

1. Add unitest
2. Add SeqExpandOpKernel