Summary:
Priliminary diff to solicit comments.
Given DB path, dump all SST files (key/value and properties), WAL file and manifest
files. What command options do we need to support for this command? Maybe
output_hex for keys?
Test Plan: Create additional ldb unit tests.
Reviewers: sdong, rven
Reviewed By: rven
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D29547
