Issues with start and end times for all-day events

[osteele]

In add-edit-page.js#132:

      if (eventData.allDay) {
        eventData.start.startOf('day');
        eventData.end.endOf('day');
      }

1. eventData.start.startOf('day') should presumably be eventData.start = eventData.start.startOf('day'), ditto for eventData.end.
2. eventData.end.endOf('day') sets the time to 23:59:59. Presumably what's wanted is actually startOf('day').
3. These times are start of (and, given (2), end of) day in local time. Presumably this should be in UTC.