Supporting PathManager in cached_path util.
Supporting PathManager in cached_path util.

Summary: Supporting PathManager in cached_path util.

Reviewed By: myleott

Differential Revision: D27895813

fbshipit-source-id: 68d7345ebb50737c53a72dcd467536f86b61e1dd

pytorch/fairseq,pytorch/fairseq,pytorch/fairseq