When adding a form typeinteger with aempty_data => 0 (aka with a int or float value) the form field will never validate correctly because theNumberToLocalizedStringTransformer will throw aTransformationFailedException because the value is not a string.

This PR fixes this problem by allowing int and float types as values inreverseTransform. Because the string only behavior was enforced by the transformer tests this is a BC change. (Personally I think that this is not a BC break that would cause problems).

Another possible fix is to add a normalizer for theempty_data option and transform a int or float to a LocalizedString but that looks/feels like a bad patch job.

I hope this PR will have less people going through there validation schema just to figure out that it's theNumberToLocalizedStringTransformer causing the problem.