Make Celerity a real application
Summary: Ref T5702. This primarily gets URI routing out of Aphront and into an Application, for consistency.
Test Plan: Loaded some pages, got static resources.
Reviewers: chad, btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T5702
Differential Revision: https://secure.phabricator.com/D10696