Stringlize 2-d tensors with Dictionary.
Stringlize 2-d tensors with Dictionary.

Summary: Pull Request resolved: https://github.com/pytorch/fairseq/pull/828

Differential Revision: D15960629

Pulled By: myleott

fbshipit-source-id: ca631651e9a90ce8ed90ca23987519001fea3656

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq