Updated it to work with varnish 4.0.1

Hi Mattias, today I decided to test Varnish 4 since I haven't touched since latest 3.x and I picked your config as a starting point. The pull request shows that there are a lot of changes, but most of them are white space reformatting.

I also added some more comments and a few tweaks, as this will be used as a template and a learning point in a presentation.

P.D. Very nice and interesting blogs BTW, your personal one and the company one.