GCE does this in its per-provider scripts; this does the same for AWS and lets
other providers do the same; I believe kube2sky requires 10.0.0.1 as a SAN.
Also fix up cert generation. It was failing during the first salt highstate when trying to chown the certs as the apiserver user didn't exist yet. Fix this by creating a 'kube-cert' group and chgrping the files to that. Then make the apiserver a member of that group.
Fixes#2365Fixes#2368