public ActionResult Configure()
        {
			var model = new ConfigurationModel();
			model.DescriptionText = _invoicePaymentSettings.DescriptionText;
			model.AdditionalFee = _invoicePaymentSettings.AdditionalFee;
			model.AdditionalFeePercentage = _invoicePaymentSettings.AdditionalFeePercentage;
            
            return View("SmartStore.Plugin.Payments.Invoice.Views.PaymentInvoice.Configure", model);
        }
		public ActionResult Configure(ConfigurationModel model, FormCollection form)
        {
            if (!ModelState.IsValid)
                return Configure();

			//save settings
			_invoicePaymentSettings.DescriptionText = model.DescriptionText;
			_invoicePaymentSettings.AdditionalFee = model.AdditionalFee;
			_invoicePaymentSettings.AdditionalFeePercentage = model.AdditionalFeePercentage;
			_settingService.SaveSetting(_invoicePaymentSettings);

            return View("SmartStore.Plugin.Payments.Invoice.Views.PaymentInvoice.Configure", model);
        }