public ActionResult LogOn(LogOnModel model)
        {
            string captcha = AccountUtil.GetCaptcha();
            if (!captcha.Equals(model.ConfirmationCode, StringComparison.OrdinalIgnoreCase))
            {
                ModelState.AddModelError(string.Empty, "驗證碼錯誤");
            }
            else
            {
                if (model.ValidateUser())
                {
                    return !String.IsNullOrWhiteSpace(model.RtnUrl)
                                ? (ActionResult)Redirect(model.RtnUrl)
                                : RedirectToAction("Index", "Admin", new { RtnUrl = HttpContext.Request["RtnUrl"] });
                }
                else
                {
                    ModelState.AddModelError(string.Empty, "帳號密碼錯誤");
                }
            }

            return View(model);
        }
        /// <summary>
        /// 測試用快速登入
        /// </summary>
        /// <returns></returns>
        public virtual ActionResult TestLogon()
        {
            LogOnModel model = new LogOnModel() { Account = "admin", Password = "******", ConfirmationCode = AccountUtil.GetCaptcha() };
            if (model.ValidateUser())
            {
                return !String.IsNullOrWhiteSpace(model.RtnUrl)
                            ? (ActionResult)Redirect(model.RtnUrl)
                            : RedirectToAction("Index", "Admin", new { RtnUrl = HttpContext.Request["RtnUrl"] });
            }
            else
            {
                ModelState.AddModelError(string.Empty, "帳號密碼錯誤");
            }

            return View("LogOn");
        }