Upgrade Mumble password hashing to bcrypt (#671)

Added transition to bcrypt-sha256 hashing for mumble passwords.
All new passwords will be hashed by bcrypt-sha256. The existing SHA-1
hashes will continue to work as a fallback for legacy password hashes.

services/modules/mumble/migrations/0005_mumbleuser_hashfn.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.4 on 2017-01-23 10:28
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mumble', '0004_auto_20161214_1024'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='mumbleuser',
+            name='hashfn',
+            field=models.CharField(default='sha1', max_length=20),
+        ),
+        migrations.AlterField(
+            model_name='mumbleuser',
+            name='pwhash',
+            field=models.CharField(max_length=80),
+        ),
+    ]