Incorporate K8S API changes.

- Importing API types from k8s.io/api
- Update client-go and apimachinery version
- Remove lib/helper and use the kubernetes one temporary

cmd/nfs-client-provisioner/provisioner.go

@@ -26,10 +26,10 @@ import (
 
 	"github.com/golang/glog"
 	"github.com/kubernetes-incubator/external-storage/lib/controller"
+	"k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/pkg/api/v1"
 	"k8s.io/client-go/rest"
 )