Role to configure port forwarding in a OpenWRT firewall.
Import this role in any host playbook to open a redirect to the
current host from the host labelled as firewall.

Example:

    - set_fact:
        firewall: 'inventory_name_of_firewall'
    - import_role: name=port_forwarding
      vars:
	name: 'stun'
	proto: 'tcp'
	port: 3478