Time controls should format end date value correctly (not 5:0 PM)

Summary: Fixes T9296

Test Plan: Create an event, change start time to 3PM, end value should update to 4:00 PM, not 4:0 PM

Reviewers: chad, epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Maniphest Tasks: T9296

Differential Revision: https://secure.phabricator.com/D15725