small change to schema
small change to schema

Summary:
as desc.

small fix in the feature_proc layer for the case when we only have one preproc type

Reviewed By: chocjy

Differential Revision: D4908933

fbshipit-source-id: 1338048fc395f85c3724721a9996ad1ee51f0f20

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