Calendar events should now surface to Feed.
Summary: Closes T7955, Calendar events should now surface to Feed.
Test Plan: Create and/or edit an calendar event, open Feed, inspect the Feed stories for the event.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7955
Differential Revision: https://secure.phabricator.com/D12597