添加contest ip限制api；

OI problem的AC，total count也算入profile了

contest/migrations/0008_contest_allowed_ip_ranges.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-11-10 06:57
+from __future__ import unicode_literals
+
+import django.contrib.postgres.fields.jsonb
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contest', '0007_contestannouncement_visible'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='contest',
+            name='allowed_ip_ranges',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=list),
+        ),
+    ]