[DON'T MERGE] [PoC] Using the concepts of LazyMap to speed up ORM internals

For reference, see https://github.com/Ocramius/LazyMap

This is just a Proof of Concept - not meant to be merged

Still checking the performance test suite.

The main advantage here is getting rid of metadata that has been shared across all the different components. If this approach is acceptable, we can limit ourselves to passing around the class metadata factory