Modify samplingTrain layer to take more general inputs
Modify samplingTrain layer to take more general inputs

Summary: As desc.

Reviewed By: kittipatv

Differential Revision: D5363486

fbshipit-source-id: cb8fa65d750e80d2bf3e9909ca9b2d83a5548099

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