Dev global step (#2100)

* assign op


AddGlobalStepOpConf


fix


ARITHMETIC_DATA_TYPE_SEQ


identity_op_conf


add ops


GenNewSnapshotName


SnapshotOp


cleanup


blob name


LearningRateScheduleOp


LearningRateScheduleKernel


LearningRateScheduleKernel


AddLearningRateScheduleOpConf


learning rate


cleanup


fix


fix

* remove total_mbn_num

* date time format

* save

* refine

* refine

* revert

* refine snapshot

* fix

* refine

* AutoGlobalStep

* refine

* GenLogicalBlobName

* AutoLearningRate

* remove JobDesc lr

* fix snapshot path

* Maybe<void>

* learning_rate blob

* remove next_model_vid


fix


fix 


fix


learning_rate

* train_conf

* fix for global step on multi nodes

* Fix optimizer initializer (#2095)

* fix optimizer initializer

* rename lars data temp bn