Implements configurable start and end hour of the dayused in schedule

app/views/admin/schedules/_day_tab.html.haml

@@ -3,13 +3,15 @@
 / use smaller cell heights for more compact grids
 - cell_height = compact_grid ? 32 : 58
 - date_event_schedules = @event_schedules.select{ |e| e.start_time.to_date.eql? date }
+- start_hour = Schedule::START_HOUR
+- end_hour = Schedule::END_HOUR
 .row
   - @rooms.each do |room|
     .col-md-2.col-xs-6
       .room-name
         - room_date_event_schedules = date_event_schedules.select{ |e| e.room == room }
         = room.name
-      - (9*cells_per_hour..18*cells_per_hour).each do |slot|
+      - (start_hour*cells_per_hour..end_hour*cells_per_hour).each do |slot|
         - hour = slot / cells_per_hour
         - minutes = (EventType::LENGTH_STEP * (slot % cells_per_hour)).to_s.rjust(2, '0')
         - time = "#{hour}:#{minutes}"