[patches] add two ipv6 nameservers

On the second hackathon we agreed to add two ipv6 nameservers:

* 2001:4ce8::53 (as250)
* 2001:910:800::12 (french data network - http://www.fdn.fr/)

Closes #15 (https://github.com/freifunk-berlin/firmware/issues/15)
Merge pull request #156 from freifunk-berlin/features/add_ipv6_nameservers

[patches] add two ipv6 nameservers