Remove the timestamp in rules.iptables

The constantly-updated timestamp causes the resource to be updated on
every Chef run. This causes a useless diff to be displayed in the
chef-client output, and it also results in the iptables rules being
re-loaded on every run.
Add an option to control if iptables is reloaded on every run
Merge pull request #20 from irccloud/remove-template-timestamp

Remove the timestamp in rules.iptables