Auth Callback and Auth URL should support tokens as well as token requests

[mattheworiordan]

Currently in the Java library it is supported, see

                if(authCallbackResponse instanceof TokenDetails)
                    return (TokenDetails)authCallbackResponse;
                if(authCallbackResponse instanceof TokenParams)
                    signedTokenRequest = (TokenParams)authCallbackResponse;
                else
                    throw new AblyException("Invalid authCallback response", 40000, 400);

[mattheworiordan]

This is implemented