Compress DNS responses and truncate them if using UDP transport

[esselius]

Using resolvable made docker stop working:

$ docker run -it gliderlabs/alpine  /bin/sh
Unable to find image 'gliderlabs/alpine:latest' locally
Pulling repository docker.io/gliderlabs/alpine
Error while pulling image: Get https://index.docker.io/v1/repositories/gliderlabs/alpine/images: dial tcp: lookup index.docker.io on 172.17.0.1:53: cannot unmarshal DNS message

Solution shamelessly stolen from: d2iq-archive/mesos-dns#173

Updating to alpine:3.2 was required because github.com/miekg/dns would not work with go-1.3.3-r1 available in alpine:3.1