WIP: Re-implementing kube-up in go

This is very much a WIP. Wanted to get comments before I get too far down any rabbit holes.

kube-up.go follows the structure of kube-up in util.sh pretty closely. My next step is to take the library stuff currently in kube_updown.go and fit it nicely into the cloudprovider abstraction.

One thing I forgot to mention in my comments yesterday: It is usually a sign that you need to refactor when you have this many arguments to a function and so many of them are the same type in a row. It would be really easy for a caller to swap the order of project/zone or size/tag and not realize it and since they are all the same type the compiler can't help.