Allow modern hunks to be stored deflated
- Used bin/hunks migrate to move some hunks over, saw ~70-80% compression on most standard hunks.
- Viewed changesets using compressed hunks.
- Profiled gzinflate() and verified the cost is trivial (<< 1ms) at least for normal diffs.
Reviewed By: btrahan
Differential Revision: https://secure.phabricator.com/D9292