ffwizard-berlin - remove firewall_create_zone()

firewall_create_zone() is not used anymore and there obsolete
firewall-defaults: add tunl0 to freifunk network
ffwizard: remove tunl0 from configuration

freifunk-defaults already set tunl0 as network of freifunk firewall zone
Merge pull request #27 from freifunk-berlin/features/firewall_tunl0

Add unreachable rules for tunl0 to olsrd-defaults