Facebook auth no longer works

[tleyden]

After couchbase/sync_gateway#580, Facebook auth is broken when running TodoLite against the master branch of sync gateway.

To reproduce:

• Run master branch of sync gateway (I have one running at http://ec2-54-166-147-121.compute-1.amazonaws.com:4984/todos, using this todolite config)
• Run TodoLite ios
• Fb login
• Add doc

Doc does not sync. The error logs in sync gateway are as follows: https://gist.github.com/tleyden/7dbbcfff4d0429333996