Add checksum to the preload tarball download
Add checksum to the preload tarball download

Check the checksum before putting the download into the cache,
leave the previous checksum file even if it is now redundant.

kubernetes/minikube,kubernetes/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube