BMUF Resetting local state param
BMUF Resetting local state param

Summary:
BMUF
1) Resetting BMUF parameters after warmup.
2) Resetting local param state after warmup.
3) Allowing user to pass block momentum value instead of gpu derived Block Momentum.

Reviewed By: skritika, mrshenli

Differential Revision: D16692026

fbshipit-source-id: d02eaf29d0e4b37007418166ec937d4bf5fe6aca

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq