Implement basic object rules for Herald

Summary:
Ref T4264. Allows you to create "Object" rules, in addition to Global and Personal rules. If you choose to create an Object rule, you'll be prompted to select an object on a new screen. You must be able to edit and object in order to create rules for it.

Ref T3506. This makes "All" the default filter for the transcript view, which should reduce confusion on smaller installs.

Test Plan:
  - Created non-object rules.
  - Created object rules.
  - Triggered object rules against matching and unmatching objects.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3506, T4264

Differential Revision: https://secure.phabricator.com/D7853