Introduce RequiredAction model

Fix #343 by no longer marking as refunded automatically

src/pretix/plugins/stripe/urls.py

@@ -1,9 +1,14 @@
 from django.conf.urls import include, url
 
-from .views import webhook
+from .views import refund, webhook
 
 event_patterns = [
     url(r'^stripe/', include([
         url(r'^webhook/$', webhook, name='webhook'),
     ])),
 ]
+
+urlpatterns = [
+    url(r'^control/event/(?P<organizer>[^/]+)/(?P<event>[^/]+)/stripe/refund/(?P<id>\d+)/',
+        refund, name='refund'),
+]