Add PCI and DMZ network configuration to panther_config

[jof]

Background

This moves the PCI and DMZ network definitions into the panther_config-based configuration system, which more easily enables downstream organizations to set their own values here.

Surprisingly, in the existing configuration, 100.1.0.0/24 is listed as a DMZ network, but this is a public IP address range belonging to Verizon Business. This seems like a dangerous and incorrect default to have set.
So, I have changed these configuration defaults to be empty -- organization-users will need to set meaningful values for their environment.

Changes

• Move PCI_NETWORKS and DMZ_NETWORKS to configuration values inside of panther_config. Users should set their own values inside of panther_config_overrides.py

[egibs]

Nice -- good catch with 100.1.0.0/24 as well. I wonder if the intended CIDR block was 10.1.0.0/24 and was entered incorrectly; either way, it's best to let customers define these ranges.