Refactor 'if false do nothing' logic in l3 scheduler db

Change-Id: I67983bb1115857ab11e3269fcbe1b20c85c93dbb
Add -s option for neutron metering rules

While adding iptables rule, cidr is added as destination for both ingress
and egress directions. Modified code to add -s for egress and -d for ingress.

Closes-bug: 1310589

Change-Id: Id9ca10855e6527d4bec689f8f9bcd6f681221954
Merge "Refactor 'if false do nothing' logic in l3 scheduler db"
Merge "Add -s option for neutron metering rules"