public ActionResult Index(CredentialLoginBinder credential, string returnUrl)
        {
            if (!this.ModelState.IsValid)
            {
                IndexViewModel model = new IndexViewModel();
                model.Credential = credential;

                return this.View(model);
            }

            bool validCredentials = Membership.ValidateUser(credential.Username, credential.Password);

            if (!validCredentials)
            {
                IndexViewModel model = new IndexViewModel();
                model.Credential = credential;

                return this.View(model);
            }

            FormsAuthentication.SetAuthCookie(credential.Username, true);

            this.Logger.InfoFormat("User '{0}' is logged in.", credential.Username);

            if (!string.IsNullOrEmpty(returnUrl))
            {
                return this.Redirect(returnUrl);
            }

            return this.urlBuilder.Admin.Home().Redirect();
        }
        public ActionResult Index(string returnUrl)
        {
            IndexViewModel model = new IndexViewModel();
            model.Credential = new CredentialLoginBinder();

            return this.View(model);
        }