Google fallback

Pull request of code for comment. 
No tests added yet but code has been checked with an app (by setting a useless domain/url for geonames - xapi.geonames.org).
For https://github.com/panthomakos/timezone/issues/27
There's a lot of duplicated code between wsgeonames and google. Maybe refactoring this out into `APIClient` classes would be good to reduce the duplication and simplify this class. I'm happy to help with that as well.