Fix puppet resource acceptance tests

The dport/sport test needs iptables-persistent pre-installed in order
for the iptables_persistent_version fact to work.

This commit also changes the test to create the rule with a comment and
with the default protocol so that the puppet resource command is
checking the existence of a resource and not creating a new one or
altering an existing one.

After those changes, checking stderr still fails because of puppet's
deprecation warnings. This commit fixes puppet.conf to avoid the
warnings so that we can actually check stderr. With that accomplished I
added checks for stderr to the other puppet resource tests since they
should now be reliable.