* 1. implement StopAll in ListenAndServOp
2. make pserver receive the SIGINT and SIGTERM from outside
3. add unittests for listen_and_serv_op in python

* 1. add blocking queue set to record queue
2. aware all blocking queue when exit and exit gracefully

* 1. Remove comment lines from blocking_queue.h
2. Implement SignalHandler and move all global vars and funcs into it

* 1. Make code follows the style check
2. Move the SignalHandler out of the unnamed namespace

* 1. Make yapf happy

* 1. Call Stop() in destructor to release the resource allocated by ListendAndServOp
2. Change exit status to EXIT_SUCCESS after handling the signal from outside
3. Remove the mis-usage of REMOVE_ITEM in unittests

* 1. use DISABLE_COPY_AND_ASSIGN
2. use program once macro only

* Add quad transform.

* Fix some syntax error.

* Fix CUDA kernel launch configure.

* Generalize geometry channels.

* Rename QuadTransform to PolygonRestore.

* Rename op.

* Rename op and fix computation.

* Modify CMakeLists.txt for box_restore op.

* Refine code:
1. rename op
2. uncomment unitest on GPU

* add create lodtensor from list

* modify book example

* unify UpsamplingBilinear2d interface specification

* unify UpsamplingBilinear2d interface specification

* fix name conventions

* small fix about computation order

* fix range in data flow analysis

* Update label role implementation to use new API

* Try trainable embedding layer

* Fix feed order

* Add infer call

* Expose bilinear operator into Python API

* delete unused lines

* delete unused lines

* fix typos

* fix name arg and typos

* add lod_tensor utility python module

* add lod_tensor test code

* add more lod tensor tests

* modify word2vec example code using new api

* add comment