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