fix(api): add certificate private key validator migration

rootfs/api/migrations/0022_add_private_key_validation.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.4 on 2017-01-11 22:19
+from __future__ import unicode_literals
+
+import api.models.certificate
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('api', '0021_appsettings_label'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='certificate',
+            name='key',
+            field=models.TextField(validators=[api.models.certificate.validate_private_key]),
+        ),
+    ]