BibFormat: use default namespace in XSL

• To be compatible with MARCXML records stored in the DB sometimes with or without namespace (and to be backward compatible with existing XSL templates), ignore MARCXML namespace of input records. See also: http://plasmasturm.org/log/259/ http://www.perlmonks.org/?node_id=530519

• Also process input MARCXML to identify empty indicators with a space character, in case it is still stored in the old way in the bibfmt table.