Summary: Hack up rocksdb_dump and rocksdb_undump utilities to get this task rolling/promote discussion.
Test Plan: Dump/undump databases recursively to see if nothing is lost.
Reviewers: sdong, yhchiang, rven, anthony, kradhakrishnan, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D37269
