Lay most groundwork for Herald object rules

Summary:
Ref T4264. This gets most of the plumbing in for "object" rules, which will bind to a specific object, like a repository or project.

It does not yet let you actually create these rules.

Test Plan: Ran `storage upgrade`, created/edited rules, browsed Herald.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4264

Differential Revision: https://secure.phabricator.com/D7847

resources/sql/patches/20131227.heraldobject.sql

@@ -0,0 +1,6 @@
+ALTER TABLE {$NAMESPACE}_herald.herald_rule
+  ADD triggerObjectPHID VARCHAR(64) COLLATE utf8_bin;
+
+ALTER TABLE {$NAMESPACE}_herald.herald_rule
+  ADD KEY `key_trigger` (triggerObjectPHID);
+