Provide an application-wide controller for Releeph

Summary: Fixes T3548. Concrete Releeph controllers currently extend either from ReleephController or PhabricatorController directly. Instead, make them all extend ReleephController. Introduce ReleephProjectController for controllers which depend on project context. Project context code which lived in ReleephController moves to ReleephProjectController.

Test Plan: Viewed list, project, releases, requests.

Reviewers: btrahan, edward

Reviewed By: edward

CC: aran

Maniphest Tasks: T3548

Differential Revision: https://secure.phabricator.com/D6472