Bug 1072757 - Implement SettingsCore

I think that using ```server``` as a namespacing type of thing here is going to be really confusing when reading the code. When I see this I immediately think that the code is storing some kind of XHR requests or making some requests to a remote resource.

My recommendation is to either rename this, or consider investigating previously used namespacing solutions. Calendar does an ok job at this [1], but we could probably do even better.

[1] https://github.com/mozilla-b2g/gaia/blob/master/apps/calendar/js/controllers/time.js#L1