Added a donut chart to the quota view

Moved morris.js out of the statistics plugin

src/pretix/control/views/__init__.py

@@ -26,3 +26,12 @@ class UpdateView(EventBasedFormMixin, edit.UpdateView):
     properly.
     """
     pass
+
+
+class ChartContainingView:
+
+    def get(self, request, *args, **kwargs):
+        resp = super().get(request, *args, **kwargs)
+        # required by raphael.js
+        resp['Content-Security-Policy'] = "script-src {static} 'unsafe-eval'; style-src {static} 'unsafe-inline'"
+        return resp