Draft: Resolve "Migrate to new data model"

Closes #246 (closed)

aleksis/apps/alsijil/migrations/0001_initial.py

 # Generated by Django 3.0.6 on 2020-05-29 10:29
 
-import django.contrib.sites.managers
 import django.db.models.deletion
 from django.db import migrations, models
 
+import aleksis.core.managers
+
 import aleksis.apps.alsijil.models
 
 
@@ -75,7 +76,7 @@ class Migration(migrations.Migration):
                 "verbose_name_plural": "Personal note filters",
                 "ordering": ["identifier"],
             },
-            managers=[("objects", django.contrib.sites.managers.CurrentSiteManager()),],
+            managers=[("objects", aleksis.core.managers.AlekSISBaseManager()),],
         ),
         migrations.CreateModel(
             name="PersonalNote",