Calendar event edit view should validate that start time preceeds end time
Summary: Closes T8023, Calendar event edit view should validate that start time preceeds end time .
Test Plan: Create Calendar event, add details, make end time be earlier than start time, try to save, get error, make sure all previously entered details are populated correctly.
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley, Blessed Reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T8023
Differential Revision: https://secure.phabricator.com/D12656