potentially fix the too many redirects issue

controllers/user.js

@@ -55,7 +55,7 @@ exports.postSignin = function(req, res, next) {
         return next(err);
       }
       req.flash('success', { msg: 'Success! You are logged in.' });
-      res.redirect(req.session.returnTo || '/');
+      return res.redirect(req.session.returnTo || '/');
     });
   })(req, res, next);
 };