Updated models and added post-save hook

migrations/0004_auto_20180301_1711.py

@@ -0,0 +1,19 @@
+# Generated by Django 2.0.2 on 2018-03-01 17:11
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0003_auto_20180301_1700'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='asset',
+            name='collection',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='assets.Collection'),
+        ),
+    ]