Added a basic permission matrix editor for events

src/pretix/base/migrations/0004_eventpermission_can_change_permissions.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0003_auto_20150602_2232'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='eventpermission',
+            name='can_change_permissions',
+            field=models.BooleanField(default=True, verbose_name='Can change permissions'),
+        ),
+    ]