WIP: Fix unmount

Unmounting was not working because unuse_data_iterate() was trying to unmount, then recurse back into itself, then check if it was mounted again. The second check would still see the fs as mounted even though it had just been unmounted, so it would try to unmount it again, which would fail. Inhibit the second mounted check.

Closes: #101 (closed)

This fixed the problem for me, but now that I think about it, I don't think the change is correct if there are multiple places where the fs is mounted. I'm not sure how to properly make sure that the dbus object is updated before checking the path again.