add judge server is_disabled field

conf/migrations/0003_judgeserver_is_disabled.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-12-24 03:44
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('conf', '0002_auto_20171011_1214'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='judgeserver',
+            name='is_disabled',
+            field=models.BooleanField(default=False),
+        ),
+    ]