Replace the usage of "names" for storage with "ids"

Ala http://issues.hibernatingrhinos.com/issue/RavenDB-1140

This isn't quite ready for merge yet, but it could definitely do with some review while I'm still on the project (I'm off on Monday for a couple of weeks)

Still outstanding that I know of

- I need to convert the storage itself to use integers
- I need to optimise look up by name (currently O(n))
- migration path