Calendar event monograms, part 1. Event default URL should be install/E{id} instead of install/calendar/view/{id}

Summary: Ref T7928, Calendar event monograms, part 1. Default event URL should be install/E{id}

Test Plan: Create calendar event, event should open with install/E{id} URL. Edit event and cancel edit, URL should remain install/E{id}.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T7928

Differential Revision: https://secure.phabricator.com/D12578