title: express-flash message not working with passport custom callback
body: <p>I'm using express 4, passport and express-flash.  When I use the canned passport middleware function and set failureFlash: true, all works fine.  But when I use a custom callback in my register function in the same routes file it doesn't work.  The messages.info object is null.</p>
  
  <p>This works fine:</p>
  
  <pre><code>    router.post('/login', passport.authenticate('local-login', {
          successRedirect: '/dashboard',
          failureRedirect: '/login',
          failureFlash: true
      }),
      function(req, res){
      }
  );
  </code></pre>
  
  <p>This results in my messages.info object being null:</p>
  
  <pre><code>    router.post('/register', function(req, res, next){
      passport.authenticate('local-signup', function(err, user, info){
          if(err){
              req.flash('info', err);
              res.render('register');
          }else{
              res.render('profile');
          }
      })(req, res, next);
  });
  </code></pre>
  
  <p>I'm using jade as my preprocessor:</p>
  
  <pre><code>    if (messages.info)
      .message.info
          span= messages.info
  </code></pre>
  
  <p>No worky!</p>