Implement shape inference function for AccumulateOp
Implement shape inference function for AccumulateOp

Summary: Implemented the sharp inference function for AccmulateOp. The output shape and type should be same as the input.

Differential Revision: D4518812

fbshipit-source-id: 11fc7ec4fad1fe3049c5a35d13c371627f9e3d11

Yangqing/caffe2,xzturn/caffe2,Yangqing/caffe2,xzturn/caffe2,davinwang/caffe2,sf-wind/caffe2,Yangqing/caffe2,pietern/caffe2,sf-wind/caffe2,davinwang/caffe2,pietern/caffe2,xzturn/caffe2,pietern/caffe2,xzturn/caffe2,pietern/caffe2,davinwang/caffe2,davinwang/caffe2,davinwang/caffe2,sf-wind/caffe2,pietern/caffe2,bwasti/caffe2,Yangqing/caffe2,sf-wind/caffe2,bwasti/caffe2,bwasti/caffe2,bwasti/caffe2,xzturn/caffe2,bwasti/caffe2,Yangqing/caffe2,sf-wind/caffe2,caffe2/caffe2