Also, the part of the schedule event is deleted and the length of the event types
changes to the nearest suitable after changing the length of the interval.
This closes#1220
Added an application helper method `time_with_timezone` to return time with the conference timezone which solves the issue of wrong timezone in `scheule.xml` and `admin/events#show`.
Fixes#1188
- Drop selected_event_schedule function
- Rename scheduled_room and scheduled_start_time to room and time as if there is no selected_schedule, the event is not scheduled.