Update file_permissions_ungroupowned to use updated unix-def behaviors

Originally requested by pbrabec some time ago
https://fedorahosted.org/scap-security-guide/ticket/134

testing:
$ ./testcheck.py file_permissions_ungroupowned.xml
Evaluating with OVAL tempfile : /tmp/file_permissions_ungroupownedD0pQj8.xml
Writing results to : /tmp/file_permissions_ungroupownedD0pQj8.xml-results
Definition oval:scap-security-guide.testing:def:100: true
Evaluation done.