Add migration.

biscuit/core/migrations/0004_group.py

+# Generated by Django 2.2.3 on 2019-07-16 11:37
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0003_split_person_user'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Group',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=30, verbose_name='Long name of group')),
+                ('short_name', models.CharField(max_length=8, verbose_name='Short name of group')),
+                ('members', models.ManyToManyField(related_name='member_of', to='core.Person')),
+                ('owners', models.ManyToManyField(related_name='owner_of', to='core.Person')),
+            ],
+        ),
+    ]