Make ownership filter consistent between relink and rimport

As of #31, `rimport` walks directories to find files to publish with no regard for who owns the file. `relink.py`, on the other hand, still filters to just the owner. This is necessary, I think, because the `rimport` makes it so commands are run as the staging owner, and thus we would need special handling to check that ownership by _the calling user_ is checked.

It may be acceptable to go either way on this: Both check ownership or neither does. It feels weird to have this obvious failure case possibly lead to situations where someone publishes someone else's file but then can't relink it, so I lean towards both checking.

Compara el filtrado de propiedad en relink.py con el recorrido de directorios en rimport, centrándote en cómo se representan el propietario del staging y el usuario que realiza la llamada. Determina si ambos comandos deberían comprobar la propiedad o si ninguno debería hacerlo y, después, verifica que la publicación y el relink gestionen de forma coherente el archivo de otro usuario.

Escrito por el modelo de indexación a partir del texto del issue.