Show unpublished conference schedule to staff.

This is an addendum to #123 to allow the `schedule_conference` view to
show unpublished conference schedules to staff members.

symposion/schedule/views.py

@@ -34,6 +34,9 @@ def fetch_schedule(slug):
 
 def schedule_conference(request):
 
+    if request.user.is_staff:
+        schedules = Schedule.objects.filter(hidden=False)
+    else:
         schedules = Schedule.objects.filter(published=True, hidden=False)
 
     sections = []