Commented Issue: Make JsonContractResolver a public class [228]

This would enable overriding the ResolvePropertyName method (see Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver) without having to reimplement the entire JsonContractResolver class. I would really like to keep its private property behavior.
Comments: We exposed the SerializerSettings, but we made our implementation of contract resolver internal. We should make it public.