Fixes metadata option. Added missing attribute.

This is the error I was getting prior to the change:
 File "./meTypeset/bin/meTypeset.py", line 97, in set_metadata_file
    metadata_file = self.gv.settings.clean_path(self.gv.concat_path(self.settings.script_dir,
AttributeError: 'GV' object has no attribute 'concat_path'