修复两步验证中的错误

account/migrations/0017_auto_20151212_2139.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9 on 2015-12-12 13:39
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('account', '0016_auto_20151211_2230'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='user',
+            name='tfa_token',
+            field=models.CharField(blank=True, max_length=40, null=True),
+        ),
+    ]