mongoose注意

 Account.register(new Account({ username : req.body.username }), req.body.password, function(err, account) {
        if (err) {
          return res.render("register", {info: "Sorry. That username already exists. Try again."});
        }

        passport.authenticate('local')(req, res, function () {
            req.session.save(function (err) {
                if (err) {
                    return next(err);
                }
                res.redirect('/');
            });
        });
    });

送出表單時，一定要有在表單裡設定 req.body.username　req.body.password　不然會Bad Request

不知道mongoose在那裡有作驗證

https://github.com/mjhea0/passport-local-express4