Summary:
Ref T13098. After libphutil/ and arcanist/ merged, some paths need to be adjusted. Try to organize things a little better, too.
Also, make `arc liberate` with no arguments just liberate all the libraries it can find.
Test Plan: Ran `arc liberate` and got a valid map rebuild, although I needed to apply some hacks on top of this to make the workflow reachable.
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13098
Differential Revision: https://secure.phabricator.com/D19690
