Vectorize rmsprop_update using Eigen
Vectorize rmsprop_update using Eigen

Summary: Replace for loop with Eigen operations in method rmsprop_update

Reviewed By: ajtulloch

Differential Revision: D4620691

fbshipit-source-id: 89cd570ecdf56a1255be4a0959ee711addc9696b

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