django 1.7: Fix csv export

meetingpoll/views.py

@@ -295,7 +295,7 @@ def exp_csv(request, poll_id):
     import csv
 
     # Create the HttpResponse object with the appropriate CSV header.
-    response = HttpResponse(mimetype='text/csv')
+    response = HttpResponse(content_type='text/csv')
     response['Content-Disposition'] = 'attachment; filename=nuages.csv'
 
     poll = get_object_or_404(Poll.objects.all(), id=poll_id)