Expose a way to retrieve the entire list of revisions via the core.Driver package

[ncatelli]

Currently, the State method on the driver ONLY returns the head of the revisions list. We should also look for a way to expose the entirety of the revisions list. This can be achieved either by:

• Adding an optional count parameter to the state method to retrieve n number of previous revisions up to and including the entire history. Possibly with a negative value returning the whole history
• A new method on the Driver interface for returning the entire history.