Test meta-domain resolution on Cirrus

[JeremyRand]

ncdns makes available some meta-domains such as this.x--nmc.bit and aia.x--nmc.bit, which do not require a Namecoin node to resolve. We should test on Cirrus that these domains resolve properly, both via direct queries to ncdns and via recursive resolvers like Unbound (with and without DNSSEC).