access_type for Google

[cabrilo]

Hello,

First of all, thank you for this great library, I really love its approach and how its written.

I have one issue though: I would like to be able to customize access_type when accessing Google Oauth2. As a matter of fact, I think it would be nice to be able to set values for all custom parameters that Google offers, e.g. access_type, approval_prompt, login_hint, etc. You can see the list here.

I'd be happy to create a pull request for this, but what would be the best way to do it? E.g. create ClientOptions->setUrlParameters(array('access_type' => 'offline', 'approval_prompt' => 'force')), or define setters and getters on \ReverseOAuth2\Client\Google like Google->setAccessType('offline'), or something completely different?

Thanks again,
Dejan