[WIP] add sequence pad op#10533

Merged

JiayiFeng merged 3 commits intoPaddlePaddle:developfrom

pkuyym:fix-10514

Aug 28, 2018

Commits on May 9, 2018

Add forward and backward.
pkuyym
committed

Commits on May 11, 2018

Enhance sequence_padding functor (CPU and GPU).
pkuyym
committed

Commits on May 24, 2018

Refine code.
pkuyym
committed