Don't block deletion of owner by default (#343)

To block deletion of synchronous GC of owner, delete permission on owner is required. We generally do want to want to require delete permision on owner. For background, check here: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/synchronous-garbage-collection.md#ownerreference

pkg/util/kubernetes.go

@@ -588,6 +588,8 @@ func EnsureOwnerReference(meta metav1.ObjectMeta, owner *core.ObjectReference) m
 	meta.OwnerReferences[fi].Kind = owner.Kind
 	meta.OwnerReferences[fi].Name = owner.Name
 	meta.OwnerReferences[fi].UID = owner.UID
-	meta.OwnerReferences[fi].BlockOwnerDeletion = types.TrueP()
+	if meta.OwnerReferences[fi].BlockOwnerDeletion == nil {
+		meta.OwnerReferences[fi].BlockOwnerDeletion = types.FalseP()
+	}
 	return meta
 }