bin/test_show_highstate.py: various improvements
- add ability to run the script as non root with sudo where needed
- add ability to run against multiple operating systems and make it run
against each declared OS and each declared location combination
- print the OS and location that it is running against
- do not fail when a show_highstate command fails. Instead, let them all
run with various combinations to show the user all the errors, and
exit with the appropriate status code