Bug 1008193 - Split out GaiaData class into a file

We should deprecate this entire class, so that when a consumer instantiates a `GaiaData` object we warn them about the deprecation and actually return them a `GaiaDataManager` object. That would mean we could remove all the methods and properties on the `GaiaData` object too. I also think using `@deprecated` is overkill in this case. See https://hg.mozilla.org/integration/mozilla-inbound/rev/bd63119d9f36 for an example of just using warnings.