Add missing import

aleksis/apps/alsijil/views.py

@@ -10,6 +10,7 @@ from django.utils.http import url_has_allowed_host_and_scheme
 from django.utils.translation import gettext as _
 from django.views.decorators.cache import never_cache
 from django.views.generic import DetailView
+from django.core.exceptions import PermissionDenied
 
 from django_tables2 import SingleTableView
 from reversion.views import RevisionMixin