site_url for a Server can now be blank.

src/gameservers/migrations/0002_auto_20150218_1635.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('gameservers', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='server',
+            name='site_url',
+            field=models.URLField(blank=True),
+            preserve_default=True,
+        ),
+    ]

src/gameservers/models.py

@@ -3,7 +3,7 @@ from django.db import models
 class Server(models.Model):
     title = models.CharField(max_length=255)
     game_url = models.URLField()
-    site_url = models.URLField()
+    site_url = models.URLField(blank=True)
 
     class Meta:
         ordering = ['-title']