Added a donut chart to the quota view

Moved morris.js out of the statistics plugin

src/pretix/plugins/statistics/signals.py

@@ -1,11 +1,9 @@
 from django.core.urlresolvers import resolve, reverse
 from django.dispatch import receiver
-from django.template import Context
-from django.template.loader import get_template
 from django.utils.translation import ugettext_lazy as _
 
 from pretix.base.signals import order_paid, order_placed
-from pretix.control.signals import html_head, nav_event
+from pretix.control.signals import nav_event
 
 
 @receiver(nav_event, dispatch_uid="statistics_nav")
@@ -26,17 +24,6 @@ def control_nav_import(sender, request=None, **kwargs):
     ]
 
 
-@receiver(html_head, dispatch_uid="statistics_html_head")
-def html_head_presale(sender, request=None, **kwargs):
-    url = resolve(request.path_info)
-    if url.namespace == 'plugins:statistics':
-        template = get_template('pretixplugins/statistics/control_head.html')
-        ctx = Context({})
-        return template.render(ctx)
-    else:
-        return ""
-
-
 def clear_cache(sender, *args, **kwargs):
     cache = sender.get_cache()
     cache.delete('statistics_obd_data')