Fix use of service command with iptables and deprecate old methods

This now uses two ways of running `service` depending on whether it is on the user's `$PATH` and an alternative command to save the rules if it is available. Also added more `@Deprecated` annotations where the obsolete `Protocol` enum was used.
```
% sudo service iptables save
% sudo /sbin/service iptables save
% sudo iptables-save
```