Created by: tensor-tang

• enable MKLDNNMatrix copy from CpuMatrix, then the MKLDNNMatrix mean and var can copy from moving mean and var.

• add MKLDNNBatchNormLayer files

• add unit test for mkldnn_batch_norm layer

• add python interface for mkldnn_batch_norm type. BTW, find a question that the comment said use_cudnn should depends on cudnn_version , but it has never been used. Maybe forget add cudnn_version >= 4007 or been removed? @luotao1

• add unit test for mkldnn_batch_norm branch test and simple net test