Add migration to remove obsolete anonymous user singleton.

mayan/apps/common/migrations/0004_delete_anonymoususersingleton.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('common', '0003_auto_20150614_0723'),
+    ]
+
+    operations = [
+        migrations.DeleteModel(
+            name='AnonymousUserSingleton',
+        ),
+    ]