Improve firewall rules for Fuel Master

Replaces hardcoded functions to create iptables
rules for Nailgun and Cobbler with firewall module
managed rules. Restricts network access to Fuel
Master for all services (except Fuel Web/API) to
Admin Network, plus restricts postgres to localhost
access only.

blueprint master-node-iptables-ruleset

Change-Id: Ib5d0c554bf97957c45b206b8bf4f6e64c9be109f
Merge "Improve firewall rules for Fuel Master"