[xwiki-devs] REST refactoring

Hi all, I did a small refactoring in the REST module which consisted in isolating the JAXB model classes in a separate module. This allows client to use JAXB classes for retrieving XML representations without dragging in all the core dependencies. The refactoring consisted in creating an xwiki-rest-model module in core, moving some files, and update the pom.xml's to make things compile. Maybe it's risky to commit it now, but if you are ok everything's ready. I include a diff so that you can check what it looks like. -Fabio