server: always use dir component in inodeRefForPath
server: always use dir component in inodeRefForPath

if the path is not split, MetadataService.Getdir will be called on a
file during openFile resulting in a nil models.Directory. a panic
happens further down when trying to index it.

alternative-storage/torus,alternative-storage/torus,coreos/torus,coreos/torus,nak3/torus-1,nak3/torus-1