make Level.short_label a SlugField

src/c3nav/mapdata/migrations/0042_auto_20171031_1507.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.6 on 2017-10-31 15:07
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mapdata', '0041_level_short_label'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='level',
+            name='short_label',
+            field=models.SlugField(max_length=20, unique=True, verbose_name='short label'),
+        ),
+    ]