增加 yolov2 部分

box数据层

annotated_box_data_layer.cpp
annotated_box_data_layer.hpp

一拆四层

reorg_layer.hpp
reorg_layer.cpp
reorg_layer.cu

损失层

region_loss_layer.hpp
region_loss_layer.cpp
region_loss_layer.cu 未支持

检测评估层

eval_detection_layer.hpp eval_detection_layer.cpp