Add unit tests for VATINField
Add unit tests for VATINField

- Add unit test for VATINField.deconstruct()
- Add unit test for VATINField.formfield()

fghaas/django-oscar-vat_moss,fghaas/django-oscar-vat_moss,arbrandes/django-oscar-vat_moss,arbrandes/django-oscar-vat_moss,hastexo/django-oscar-vat_moss,hastexo/django-oscar-vat_moss