Integrate django-scopes (#1319)

* Install django-scopes

* Fix tests.api

* Update tasks and cronjobs

* Fix remaining tests

* Remove unused import

* Fix tests after rebase

* Disable scopes for get_Events_with_any_permission

* Disable scopes for a management command

src/pretix/plugins/pretixdroid/forms.py

@@ -1,6 +1,9 @@
 from django import forms
 from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
+from django_scopes.forms import (
+    SafeModelChoiceField, SafeModelMultipleChoiceField,
+)
 
 from pretix.control.forms.widgets import Select2
 from pretix.plugins.pretixdroid.models import AppConfiguration
@@ -16,6 +19,10 @@ class AppConfigurationForm(forms.ModelForm):
             }),
             'app': forms.RadioSelect
         }
+        field_classes = {
+            'items': SafeModelMultipleChoiceField,
+            'list': SafeModelChoiceField,
+        }
 
     def __init__(self, **kwargs):
         self.event = kwargs.pop('event')