Summary:
Ref T2769. Move all of this stuff into Adapters and get rid of the hard-coded classes.
I cheated in two places.
Test Plan: Edited and activated Herald rules.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran, chad
Maniphest Tasks: T2769
Differential Revision: https://secure.phabricator.com/D6688
