Provide basic infrastructure for moving PHIDs, Handles and Object Names to applications

Summary:
See discussion in T2715. Currently, PHIDs are all hard coded in the PHID application. In the long run, we need to move them out into actual applications.

A specific immediate issue is Releeph, which uses a very very old and very broken mechanism to inject PHIDs in a way that only sort of works.

Moving forward, every PHID type will be provided by a `PhabricatorPHIDType` subclass, which will manage loading it, etc.

This also moves toward cleaning up the "load objects by name" (where "name" means something like `D12`) code, which is an //enormous// mess and spread across at least 4-5 callsites.

Test Plan: Used `phid.lookup` and `phid.query` to load Slowvotes.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D6502
Fix an issue with handle loads; the inner loop expects `$objects` to have only objects of the given type.

Auditors: btrahan
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
Use ApplicationSearch in Releeph project list

Summary: Ref T3092. Convert Releeph project list to ApplicationSearch.

Test Plan: {F50333}

Reviewers: btrahan, edward

Reviewed By: edward

CC: aran

Maniphest Tasks: T3092

Differential Revision: https://secure.phabricator.com/D6474