Add sale_gift_card module

issue9257
review315331002

exceptions.py

@@ -4,6 +4,14 @@
 from trytond.model.exceptions import ValidationError
 
 
+class TemplateValidationError(ValidationError):
+    pass
+
+
+class ProductValidationError(TemplateValidationError):
+    pass
+
+
 class UOMValidationError(ValidationError):
     pass