R1:934285a6d3d2

Mark some PhabricatorApplication methods as final

Summary: I don't believe that any subclass should override these methods.

Test Plan: `arc unit`

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D13265