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
guestbook-go source is separate from k8s code base. In the sense that you do not need to compile the example source to use either k8s or the guestbook-go example. The only time you'll want to compile the guestbook source is when you want to update the registry image containing the binary and html/css/js on Docker Hub.

So I believe that these do no need to be vendored into the Godeps directory. Kind of the same like guestbook-php example.