[hibernate-dev] OGM abstraction contract

I've made some progress on the abstraction contract between OGM and the underlying store. I've introduced the notion of Tuple that can then be converted in whatever the store pleases (AtomicMap for example in Infinispan's case). Let me know if you think that's going in the right direction https://github.com/emmanuelbernard/hibernate-ogm/tree/OGM-69 Note that I have not converted associations yet which is why some code esp in OgmCollectionPersister copy data back and forth between the Tuple model and the Map model.