Add Command line API

[martinheidegger]

It would be nice to have a good command line API that functions pretty simply like:

$ hyper-dns hyper://datproject.org
{
  "hyper": "ab123c...404eff"
}

etc.

Considering #4, it may be good (optionally?) return a JSON stream instead of an object, as the results may "trickle" in.

Considering #3, it may be good to optionally start a hyper-dns compatible lookup server?