Fix raven integration

src/pretix/base/__init__.py

@@ -1,4 +1,5 @@
 from django.apps import AppConfig
+from django.conf import settings
 
 
 class PretixBaseConfig(AppConfig):
@@ -17,6 +18,10 @@ class PretixBaseConfig(AppConfig):
         except ImportError:
             pass
 
+        if hasattr(settings, 'RAVEN_CONFIG'):
+            from ..sentry import initialize
+            initialize()
+
 
 default_app_config = 'pretix.base.PretixBaseConfig'
 try: