understand usage of the state param on authorization request

[aoberoi]

most likely this should be tied into #3, but at this point i haven't even seen it used.

[aoberoi]

the main use case i am interested in is storing the requested URL so that after authentication/authorization and after the user arrives at the callback URL, they can be redirected back to the initially requested URL that caused the authentication/authorization request.

[aoberoi]

info about this topic: http://www.twobotechnologies.com/blog/2014/02/importance-of-state-in-oauth2.html

[aoberoi]

looks like the super class has a built-in implementation: SessionStore. we should just have to set the state option to true. of course, this means the application must use session middleware.