add some more specs for the hardening code

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
be more verbose on what to test

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
be more verbose on what to test

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
protect agains nil

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
this is sufficient to check against g-w and o-rwx since we update 6 and 7

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
change to rubocop ~ 0.27.1

TelekomLabs-DCO-1.1-Signed-off-by: Edmund Haselwanter <me@ehaselwanter.com> (github: ehaselwanter)
Merge pull request #9 from ehaselwanter/improve-spec-tests

add some more specs for the hardening code