public ActionResult LogOff()
        {
            var login = new Login();
            login.LogOut();

            return this.RedirectToHome();
        }
        public ActionResult Login(LoginViewModel model, string returnUrl)
        {
            if (!ModelState.IsValid)
                return this.RedirectToAction("Login", new { returnUrl });

            var login = new Login();
            var loginResult = login.LogIn(model.UserName, model.Password, model.RememberMe);
            if (loginResult)
                return Url.IsLocalUrl(returnUrl) ? this.Redirect(returnUrl) : this.RedirectToHome();

            ModelState.AddModelError("", "The user name and password is not matched.");
            ViewBag.ReturnUrl = returnUrl;
            return View();
        }