Without this we end up in weird cases where the viewer gets a cache
hit and never request the object data, creating link heirarchies where
the viewer knows about all the prims but Hippolyzer only knows some
of them and orphans them.
Since we don't know what viewer the user is using, we scan around
the disk for object caches and try to use those. 99% of the time the
connection will be coming from localhost so this is fine.
Fixes#11
