Google auth

Update google geocoding logic to support version 3 of the api for business accounts:

- `client_id` param must be sent with url
- `key` param is no longer sent with url, instead a signed version of the url is created using the key and sent as a `signature` param

Without these changes all geocoding requests when a `key` is present result in an Invalid Credentials error.

I also upgraded the rake gem so I could run `bundle exec rake` to run tests as well.


References:

https://developers.google.com/maps/articles/geocodingupgrade#whats_new_in_version_3_of_the_geocoding_api

https://developers.google.com/maps/documentation/business/webservices#digital_signatures