Moved SaleForm code to Controller, have to put Exception handlers for PermissionException

Tanshu.Accounts.PointOfSale/Authentication/PermissionException.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Tanshu.Accounts.PointOfSale
+{
+    public class PermissionException : Exception 
+    {
+        public PermissionException(string message)
+            : base(message)
+        {
+        }
+        
+    }
+}