* Cross Entropy Wrong

* Fix XE

* Polish gradient check for xe

* Fix compile

* Init

* Stash

* Polish SaveLoadOp

* Fix CI

* Polish code

* Save GPU Tensor

* Stash

* Fix CI

* Adding the L2 loss operator for L2 regularization
* Renaming l2_loss op to squared_l2_norm_op
* Addressing code review feedback

enable mkldnn_batch_norm

fix sparse update size

* Removing survey out of the design doc and fixing typos
* Fix Typos

"correct the description"

Fix pserver SGD with momemtum checkpoint recover.

* Adding nesterov momentum to python momentum wrapper
* Fixing optimizer test after merge

* init cudnn batch norm op

* rename batch_norm_cudnn_op.cc batch_norm_op.cu

* correct name style

* add ExtractNCWHD, simplify code

* fix ExtractNCWHD

* use CUDNN_ENFORCE instead of PADDLE_ENFORCE

Fix new remote updater sending all 0 param / grad to pserver

Fix new pserver having random momemtum initial values

fix package name bug

add detailed log for the pserver

Go master, pserver, trainer: switch to log15, away from logrus

* 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

Fix parameter server checkpoint serialization crash

* Extract apply_backward_pass to backward.py

Rename apply_backward_pass to append_backward_ops

* Fix CI

* Update design doc