make GetComputedParams work like GetParams
make GetComputedParams work like GetParams

Summary: GetComputedParams tests namescopes with equality while GetParams tests with a prefix.  Switching GetComputedParams to also use a prefix so that both functions have similar usages.

Reviewed By: akyrola

Differential Revision: D5389816

fbshipit-source-id: 0e43e4b491fccbad3b855b6b735dc2b91d7626c9

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