s/apiservers/api_servers/ in Salt

It looks like api_servers finally won this battle. Kill off the
last remaining places passing it, but allow the kubelet Salt to
accept apiservers for a period of time.

(This was bothering my OCD.)

cluster/vagrant/provision-minion.sh

@@ -70,7 +70,6 @@ grains:
   etcd_servers: '$(echo "$MASTER_IP" | sed -e "s/'/''/g")'
   api_servers: '$(echo "$MASTER_IP" | sed -e "s/'/''/g")'
   networkInterfaceName: eth1
-  apiservers: '$(echo "$MASTER_IP" | sed -e "s/'/''/g")'
   roles:
     - kubernetes-pool
   cbr-cidr: '$(echo "$CONTAINER_SUBNET" | sed -e "s/'/''/g")'