Update geocoding to use Google's Geocoding API V3. 

Hey Alex, awesome project! We are thinking about adopting this for the Long Island Startup community here in New York. Hopefully I can contribute to this project, even in a small way. 

This pull request updates geocode.php to use Google's Geocoding API V3. I think it simplifies the xml parsing by not requiring a split on the coordinates. I also hit some problems where I was getting some invalid key requests (610 error code). Googles new API doesn't require a key. 

Google Geocoding Docs: https://developers.google.com/maps/documentation/geocoding/

I hope this request finds its way into the project. 

Thanks!