change shell var MINION_SCOPES to user setable

Because bash arrays may not be environment variables
 (see: <https://stackoverflow.com/questions/5564418/exporting-an-array-in-bash-script>)
 we have to change the MINION_SCOPES array to a string
* prefers aliases instead of full URLs for scopes

tested under GKE, needs GCE testing

Close #10458

cluster/gce/debian/helper.sh

@@ -120,7 +120,7 @@ function create-node-instance-template {
   if [[ -n ${1:-} ]]; then
     suffix="-${1}"
   fi
-  create-node-template "${NODE_INSTANCE_PREFIX}-template${suffix}" "${scope_flags[*]}" \
+  create-node-template "${NODE_INSTANCE_PREFIX}-template${suffix}" "${scope_flags}" \
     "startup-script=${KUBE_ROOT}/cluster/gce/configure-vm.sh" \
     "kube-env=${KUBE_TEMP}/node-kube-env.yaml"
 }