RFC. Fully customizable oauth token class.

[gassan]

The code was reviewed, so that OAuthToken is fully replaceable by any other AppOAuthToken, that only should be extended from AbstractOAuthToken. Use the resource owner's option token_class to change it.

[stloyd]

I'm not sure it's worth it. It adds big maintenance layer for use, while in matter of end-user use cases it will be like one on 1000 of usages.