Opt-in approve your own Differential revisions
Summary: Did exactly what @epriestley suggested in T1428#2.
Test Plan: Turn it on in your config, post a revision, accept it. Turn it off in your config, post a revision, can't accept it.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Korvin
Differential Revision: https://secure.phabricator.com/D2900