Option to specify API server

Useful for odd locales. Haven't looked into others except China, but due to China's isolationist policies, a special server must be used - https://developers.google.com/maps/faq#china_ws_access (along with care to convert from GCJ-02 to WGS-84, but that's beyond the scope of this package; more at http://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China).

So just an option to point to a custom API server, or indicate a locale if China is the only corner case.