* Add CUDA implementation for generate_proposals_op.
* Clean code.
* Update code.

* Enhence generate_proposal_labels_op
* Fix bug in generate_proposals_op
* Refine rpn_target_assign_op.
* by Bu Xingyuan, Wang Guanzhong and Dang Qingqing

* Fix bug in generate_proposals_op.
* Fix data type for RoIs.
* Refine and fix rpn_target_assign_op.
* Add the missing file bbox_util.h
* Rename BoxEncoder to BoxToDelta

* remove template operator

* "fix compile"

* "fix ci"

* "fix ci"

* Add proposals generation operator for Faster-RCNN.