move over to extending the SerializationDefinition

WIP

means we dont have this api problem


        Configure.With(b => b.UseSerialization<Json>(c => c.XmlSettings(
            settings => settings.DontWrapRawXml())));

new api would be

    Configure.With(b => b.UseSerialization<Xml>(c => c.DontWrapRawXml()));

thoughts?