Optional camelization of roots and attributes

I'd love some quick feedback on this since I really need this functionality in a current project. I do not want to have to set the key for every attribute in every serializer in the project I am working on :)

I will later add possibility of overriding the `render json: @someobject, camelize: true` but that got a little more complicated than I have time for right now. I still need that functionality just not critical right now.