Upgrade DummyLMTask to Hydra (#1415)
Upgrade DummyLMTask to Hydra (#1415)

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/1415

Test Plan: Imported from OSS

Reviewed By: alexeib

Differential Revision: D24833480

Pulled By: myleott

fbshipit-source-id: 007623168467d18166b20ef99f54388eb9d8008a

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq