* The Schedule object is deprecated in 2.18 and ScheduleRef is introduced,
update script to generate rules accordingly.
* Some shell script improvements.
Using iptables --list without -n takes a long time
on some configurations during boot up which is a problem.
This commit resolves this by not trying resolve hostnames
as it is not necessary for the functionality.
It also splits up the check in two: one for IPv4 and one
for IPv6 to make the logic more robust and fail-safe.
following cases/bugs are handled in this change:
1. Ignore schedule if access_policy is deny
2. For access policy allow, with schedule, deny for time outside
the defined schedule.
3. Default value for days
4. Handle scenario when start time is not defined by initializing
the start time to 00:00
5. Handle scenario when duration is not defined
