Federated Login Enhancements

With a little more reading and experimenting I think I've refactored the pattern into a slightly more general solution that covers startup, login and logout states properly (github updated).  Code seems robust enough -- need to test a bit under various network error states.

Next up is to wire in another social provider or two (google+ and twitter).  And then to experiment with identity merge -- how to recognize multiple authenticated userIds and then join them into a single entity.

As of this point, I'm fairly certain the auto-refreshing temporary AWS credentials are loaded and working -- seems ready to use with a sensor stream to Kinesis for example.

As a footnote, my first dabbling in Swift is encouraging.  Yes, some sort of a cross of C, Java, ObjectiveC, Javascript, heck, even Gosu.  I only know enough to be dangerous, so time to read the language spec to see what I'm missing.