Rewrite of the Guestbook example in Go

This is a Go version of the Guestbook example. The readme has been ported over from the existing one.

#1271
I think deploy.sh and destroy.sh should not be merged. I have used them for quickly copying commands from. Running these scripts as is does not provide the desired effect because the services env vars are unavailable to slaves if master doesn't start soon enough. Maybe README can provide a tldr section at the end instead. I'll pull these two scripts out when you want to merge this.