function transformed(e, t) {
      pass(i + 1, e, t);
    }
Registers a function used to transform auth info.

In some circumstances authorization details are contained in authentication
credentials or loaded as part of verification.

For example, when using bearer tokens for API authentication, the tokens may
encode (either directly or indirectly in a database), details such as scope
of access or the client to which the token was issued.

Such authorization details should be enforced separately from authentication.
Because Passport deals only with the latter, this is the responsiblity of
middleware or routes further along the chain.  However, it is not optimal to
decode the same data or execute the same database query later.  To avoid
this, Passport accepts optional `info` along with the authenticated `user`
in a strategy's `success()` action.  This info is set at `req.authInfo`,
where said later middlware or routes can access it.

Optionally, applications can register transforms to proccess this info,
which take effect prior to `req.authInfo` being set.  This is useful, for
example, when the info contains a client ID.  The transform can load the
client from the database and include the instance in the transformed info,
allowing the full set of client properties to be convieniently accessed.

If no transforms are registered, `info` supplied by the strategy will be left
unmodified.

Examples:

    passport.transformAuthInfo(function(info, done) {
      Client.findById(info.clientID, function (err, client) {
        info.client = client;
        done(err, info);
      });
    });

@api public