Timezones are globally added to the ical export

app/views/events/index.ics.haml

@@ -1,8 +1,14 @@
 :ruby
+  require 'icalendar/tzinfo'
+
   # Create a calendar with an event (standard method)
   cal = Icalendar::Calendar.new
   @events.each do |event|
     tzid = event.region.tzid
+    tz = TZInfo::Timezone.get tzid
+    timezone = tz.ical_timezone event.start_time
+    cal.add_timezone timezone
+
     cal.event do |e|
       e.dtstamp     = Icalendar::Values::DateTime.new event.decision_time, tzid: tzid
       e.uid         = "#{event.id}@#{request.domain}"