Make PhabricatorBotFeedNotificationHandler work with new PhabricatorApplicationTransactionFeedStory
Summary: Depends on D8521
Test Plan: ran with handler enabled and phabot posted stories
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Subscribers: aran, epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D8524