Hot fix: Merge mfs_dir with basename, not with absolute path

[guillermo-carrasco]

dname is an absolute path, therefore when doing:

    os.path.join(config.get('mfs_dir'), dname)

As both mfs_dir and dname are absolute paths, os.path.join was returning the second argument. So I was rsynching to the same location, not to MooseFS.