migrate to postgres json field

contest/migrations/0006_auto_20171011_1214.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-10-11 12:14
+from __future__ import unicode_literals
+
+import django.contrib.postgres.fields.jsonb
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contest', '0005_auto_20170823_0918'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='acmcontestrank',
+            name='submission_info',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+        migrations.AlterField(
+            model_name='oicontestrank',
+            name='submission_info',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict),
+        ),
+    ]