set lr for each epoch by using input dictionary parameter
set lr for each epoch by using input dictionary parameter

Summary: [Manual LR Scheduler] set lr for each epoch by using input dictionary parameter

Differential Revision: D25047764

fbshipit-source-id: 4b8ccfa1b1f5db99d73fdb478caa2c6ea8d80a50

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq