[ffwizard] freifunk-berlin/firmware#15 dns config

Use dns server from profile for wifi ap bridge, too. Also use these
dns servers even if there is dns provided by dhcp on wan.
[ffwizard] freifunk-berlin/firmware#15 dns config

dns config is only needed on one interface. peerdns is assigned
to wan interace now.
[ffwizard] freifunk-berlin/firmware#15 dns config

read just interface config needed from profile
Merge pull request #4 from freifunk-berlin/nameserverconfig

dns config