- Added optional state parameter and redirect uri override in Google Provider

With these changes it's possible with some url rewriting to create a single entrypoint for a multi domain environment. The optional state parameter is documented by Google and will be send back by Google unmodified after authentication.

After adding the state param i noticed the redirect_uri config paremeter wasn't used by the provider when Hybridauth tries to validate the response from Google in the auth.done process. I added an extra line to inject the redirect_uri directly into the api so the correct redirect uri is used on all requests.