(#11093) Improve log_level property so it converts names to numbers

(#11093) Improve log_level property so it converts names to numbers

Previously the log_level property was constantly reloading due to the fact
that iptables was converting names to numbers. So unless you were using
numbers in your log_level setting, it was constantly telling you it needed
to be changed.

Now we convert the names to numbers in the munge so when comparing it will
always hopefully match.

Also, the default value when the jump value is 'LOG' is now set to 4 (warn)
based on iptables own defaults.