Patch Set 4: Looks good to me, but someone else must approve; IP review completed

We're now at almost 100% test coverage in RefDirectory.  RefDirectoryTest alone covers everything except writing, the writes are covered elsewhere right now by existing tests.  

Eventually we need to get the writes test by RefDirectoryTest as well.  But I'd rather get the API changed and passed through first... so we're really not any worse off at this point.

So I think this is read to be merged.