Fix up to make getting started a little easier

[dsyer]

I found it quite difficult to get started using ratpack so here are the changes I made to make it work for me, plus a small change to the README (which obviously needs updating in other ways). I started on the vertx branch because that's the one that seems to be active. Hope that makes sense.

[ldaley]

Thanks Dave,

I'm in the middle of some pretty heavy work on this. I'll pull this in in a little bit and improve the readme.

Thanks for taking the time to submit.