public ActionResult Login(LoginModel model, string returnUrl)
        {
            if (ModelState.IsValid)
            {
                try
                {
                    KullaniciBLL kullanici_BLL = new KullaniciBLL();

                    if (kullanici_BLL.KullaniciKontrolü(model))
                    {
                        new UserAuth().SignIn(model, Authentication);
                        return(RedirectToAction("Index", "Home"));
                    }
                    else
                    {
                        ViewBag.Message = "Hatalı Giriş";
                        return(View(model));
                    }
                }
                catch (Exception e)
                {
                    throw;
                }
            }
            return(View(model));
        }