Make LoadModelFrom setup the object if possible.

Similar to PR #43, this allows for tombstone Vclocks to be setup inside a
new object.  The same error is returned as before, however if an object
was successfully fetched, it make sure the model is also able to be used
immediately.

I'm starting this pull request with the fix, but I don't think it is mergable yet.  I'm looking for comments first, specifically:
 - What do you need for a test (if necessary)?  I assume something similar to the one in #43?
 - Should the logic for setting up a model be pulled out to a generic function?  It seems to be used frequently.
 - Should I mark the NewModel functions as deprecated, to encourage people to use LoadModelFrom?