Summary: Closes T7943, Canceling calendar event should deactivate the event instead of destroying data.
Test Plan: Create an event, cancel it, see changed status icon, query for active events, event should not appear, query for deactivated events, event should appear in results.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7943
Differential Revision: https://secure.phabricator.com/D12604
