This is a breaking change for people using the API (sorry), but is
hopefully a simple search and replace:
"k8s.io/kops/upup/pkg/api"
-> api "k8s.io/kops/pkg/apis/kops"
"k8s.io/kops/upup/pkg/api/registry"
-> "k8s.io/kops/pkg/apis/kops/registry"
This is the "correct" place for it in the k8s API infrastructure - we
are working towards a versioned API here.