Add the ability to pass additional URL parameters to the authorize() call

Hello,

I've modified the authorize() call to allow for additional URL parameters that you may not want to include in the request_token_params instance variable.  This allows you to have one OAuthRemoteApp instance that can be used with a variety of query parameters.  For example, with Google OAuth, I'm able to pass prompt="none" for authentication only, and prompt="consent" when I want to prompt the user for access.

Please let me know if you have any questions about my use case or the changes themselves.

-Scott