* init batch norm op
* prepare input output
* compute mean_out var_out save_mean save_var on CPU
* active is test
* use eigen to do computation
* complete batch norm forward
* set default momentum to 0.9
* add batch norm grad op in CPU
* add tensor_format and NHWC support, add python test
* add test training
* add batch norm gradient test
* improve comment, fix foward Python UnitTest
* add gradient test
* fix eigen warning
* follow name style
* fix a bug
* change float to T
* add simple forward test
* test with different place
* add backward test
* refine python test
* remove old python test code
* code clean
* follow code style
* update comment
Luo Tao
Liu Yiqun
Qiao Longfei
helinwang
qijun
liaogang