fixed bug in gup implementation and pass test
	modified:   include/caffe/loss_layers.hpp
	modified:   src/caffe/layers/hinge_rank_loss_layer.cpp
	modified:   src/caffe/layers/hinge_rank_loss_layer.cu
	modified:   src/caffe/test/test_benchmark.cpp
	modified:   src/caffe/test/test_dot_product_similarity_layer.cpp
	modified:   src/caffe/test/test_hinge_rank_loss_layer.cpp
for gpu implementation cannot speed up and has lower computational
precision, so it is removed
	modified:   include/caffe/loss_layers.hpp
	deleted:    src/caffe/layers/hinge_rank_loss_layer.cu
	modified:   src/caffe/test/test_hinge_rank_loss_layer.cpp