Allow users to add map styles

Hello! I love this app and have been using with pleasure for a few months now.

Given the recent [emergence](http://mapstack.stamen.com/) and [development](http://www.mapbox.com/tour/) of services that offer map tile hosting, I was wondering whether there's interest in allowing users to add their own custom Map Styles. I'd love to be able to design tiles in [TileMill](http://www.mapbox.com/tilemill/) and use them in Satellite Eyes.

The most complicated aspect of this feature would be a UI to allow people to add/remove custom Map Style by URL, but I don't think it would too difficult.

Let me know if you're interested, and if so I may submit a pull request. Thanks!