Use ws_nbytes_limit (called cudnn_ws in args).
Use ws_nbytes_limit (called cudnn_ws in args).

Summary:
cudnn_ws args was already there. This PR only uses that args when model is created.
Closes https://github.com/caffe2/caffe2/pull/164

Differential Revision: D4598443

Pulled By: Yangqing

fbshipit-source-id: c2e83f73059360ecf2fedf2c62be7cacbb4034ca

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