**What this PR does / why we need it**:

Remove kubectl's dependence on pkg/api/helper, as part of
broader effort to isolate kubectl from the rest of k8s.
In this case, the code becomes private to kubectl; nobody else uses it.

**Which issue this PR fixes**

Part of a series of PRs to address kubernetes/community#598

**Special notes for your reviewer**:

**Release note**:
```release-note
NONE
```

pkg/kubectl/rolling_updater.go

@@ -32,13 +32,13 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/util/integer"
 	"k8s.io/kubernetes/pkg/api"
-	"k8s.io/kubernetes/pkg/api/helper"
 	"k8s.io/kubernetes/pkg/api/v1"
 	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
 	coreclient "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset/typed/core/internalversion"
 	"k8s.io/kubernetes/pkg/client/retry"
 	client "k8s.io/kubernetes/pkg/client/unversioned"
 	deploymentutil "k8s.io/kubernetes/pkg/controller/deployment/util"
+	"k8s.io/kubernetes/pkg/kubectl/util"
 )
 
 const (
@@ -627,7 +627,7 @@ func CreateNewControllerFromCurrentController(rcClient coreclient.ReplicationCon
 		newRc.Spec.Template.Spec.Containers[containerIndex].ImagePullPolicy = cfg.PullPolicy
 	}
 
-	newHash, err := helper.HashObject(newRc, codec)
+	newHash, err := util.HashObject(newRc, codec)
 	if err != nil {
 		return nil, err
 	}