alpha: bump to latest (64) COS image for GCE
alpha: bump to latest (64) COS image for GCE

aledbf/kops,blakebarnett/kops,justinsb/kops,chrislovecnm/kops,blakebarnett/kops,tsupertramp/kops,mad01/kops,kubernetes/kops,aledbf/kops,robinpercy/kops,robinpercy/kops,chrislovecnm/kops,robinpercy/kops,kubernetes/kops,gambol99/kops,blakebarnett/kops,mad01/kops,gambol99/kops,justinsb/kops,blakebarnett/kops,tsupertramp/kops,mad01/kops,chrislovecnm/kops,tsupertramp/kops,tsupertramp/kops,justinsb/kops,mad01/kops,robinpercy/kops,gambol99/kops,kubernetes/kops,aledbf/kops,gambol99/kops,chrislovecnm/kops,aledbf/kops