Summary: Depends on D19423. Ref T12164. Adds controllers capable of listing and editing `PhabricatorRepositoryIdentity` objects. Starts creating those objects when commits are parsed.
Test Plan: Reparsed some revisions, observed objects getting created in the database. Altered some `Identity` objects using the controllers and observed effects in the database. No attempts made to validate behavior under "challenging" author/committer strings.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T12164
Differential Revision: https://secure.phabricator.com/D19429
