use core client with explicit version globally

Author: kevin-wangzefeng

pkg/volume/cinder/cinder_util.go

@@ -144,7 +144,7 @@ func getZonesFromNodes(kubeClient clientset.Interface) (sets.String, error) {
 	// TODO: caching, currently it is overkill because it calls this function
 	// only when it creates dynamic PV
 	zones := make(sets.String)
-	nodes, err := kubeClient.Core().Nodes().List(metav1.ListOptions{})
+	nodes, err := kubeClient.CoreV1().Nodes().List(metav1.ListOptions{})
 	if err != nil {
 		glog.V(2).Infof("Error listing nodes")
 		return zones, err