invites: Add backend for multiuse admin invites.

zerver/migrations/0207_multiuseinvite_invited_as.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.18 on 2019-02-06 21:49
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('zerver', '0206_stream_rendered_description'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='multiuseinvite',
+            name='invited_as',
+            field=models.PositiveSmallIntegerField(default=1),
+        ),
+    ]