Fix for rspec-system-puppet 0.3.x

Signed-off-by: Ken Barber <ken@bob.sh>
(#20125) Add archlinux firewall class and unit test
(#20125) Use PATH to find (ip|ip6)tables for (ip|ip6)tables provider
(#20125) Use PATH to find (ip|ip6|eb)tables for chain provider
(#20125) Add persistence support for Archlinux platform

This only works with facter 1.7.0-rc1 and up because os_key isn't
properly defined in facter 1.6.18 on Archlinux (it's set to Linux).