MPIConstantFill -> ConstantFill
MPIConstantFill -> ConstantFill

Summary:
(this is due to an earlier blind vim find-replace error)
Closes https://github.com/caffe2/caffe2/pull/709

Differential Revision: D5159055

Pulled By: Yangqing

fbshipit-source-id: f188b7bebf79a45825568ba96a71b535fe4e3aad

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