Modernize some OAuth Server code

Summary:
Ref T7303. This inches toward properly-behaved cluster logout.

• Use IDs instead of PHIDs in URIs.
• Slightly more modern code.
• Fix some crumb stuff.

Test Plan: Created, edited, viewed, deleted, showed secret for, authorized, test-auth'd an application.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T7303

Differential Revision: https://secure.phabricator.com/D15592