public ActionResult Configure()
        {
            var model = new ConfigurationModel();
            model.UseSandbox = _paypalStandardPaymentSettings.UseSandbox;
            model.BusinessEmail = _paypalStandardPaymentSettings.BusinessEmail;
            model.PdtToken = _paypalStandardPaymentSettings.PdtToken;
            model.PdtValidateOrderTotal = _paypalStandardPaymentSettings.PdtValidateOrderTotal;
            model.AdditionalFee = _paypalStandardPaymentSettings.AdditionalFee;
            model.AdditionalFeePercentage = _paypalStandardPaymentSettings.AdditionalFeePercentage;
            model.PassProductNamesAndTotals = _paypalStandardPaymentSettings.PassProductNamesAndTotals;
            model.EnableIpn = _paypalStandardPaymentSettings.EnableIpn;
            model.IpnUrl = _paypalStandardPaymentSettings.IpnUrl;

            return View("Nas.Plugin.Payments.PayPalStandard.Views.PaymentPayPalStandard.Configure", model);
        }
        public ActionResult Configure(ConfigurationModel model)
        {
            if (!ModelState.IsValid)
                return Configure();

            //save settings
            _paypalStandardPaymentSettings.UseSandbox = model.UseSandbox;
            _paypalStandardPaymentSettings.BusinessEmail = model.BusinessEmail;
            _paypalStandardPaymentSettings.PdtToken = model.PdtToken;
            _paypalStandardPaymentSettings.PdtValidateOrderTotal = model.PdtValidateOrderTotal;
            _paypalStandardPaymentSettings.AdditionalFee = model.AdditionalFee;
            _paypalStandardPaymentSettings.AdditionalFeePercentage = model.AdditionalFeePercentage;
            _paypalStandardPaymentSettings.PassProductNamesAndTotals = model.PassProductNamesAndTotals;
            _paypalStandardPaymentSettings.EnableIpn = model.EnableIpn;
            _paypalStandardPaymentSettings.IpnUrl = model.IpnUrl;
            _settingService.SaveSetting(_paypalStandardPaymentSettings);

            return View("Nas.Plugin.Payments.PayPalStandard.Views.PaymentPayPalStandard.Configure", model);
        }