Shows a list of items in a given git directory
This "works", but it's wrong

Presently it's using the index to pull files from the repo,
and thereby getting anything that ever had a reference.

I'd much rather show the current state of master,
so I'll be changing it to do that.

Also, it's looking up the files in the file system,
which is bad because this can't be used on bare repos,
 and since I'm using the index it's looking for files that don't exist.
This now works off of the status of the master branch.

Also correctly pulls stuff from the git object store.
Won't work with nested paths or anything like that yet.