Adding some filters and queries to Macro application

Summary:
Fixes T2778

Introduces PhabricatorMacroQuery, which should consolidate all queries regarding macros

Adds PolicyInterface to PhabricatorImageMacro, as else the query would fail (we should consider adding it to the ApplicationTransaction instead, if that was ever planned)

Adds Active Macros filter, making it the default

Adds My Macros filter. You may ask why it overwrites $authors. Well, I did not want the page jump to the conclusion that it is a search result. It is one more or less, but the filter would jump to seach instead of my. If you want My Macros removed, tell me. It is useful only to heavy-macro-uploaders-and-users though. Five or six people in http://secure.phabricator.(org|com), and an estimated dozen and a half at bigger installs.

Test Plan: created multiple macros from multiple authors, disabled them at will. browsed around, verified that Macros only appeared in the right filters and that nothing else broke.

Reviewers: epriestley, chad, btrahan

CC: aran, Korvin

Maniphest Tasks: T2778

Differential Revision: https://secure.phabricator.com/D5409