Update Kubernetes to 493ee8b28560c118cebd2165ba9ef0959cfa2bc3

Signed-off-by: Lantao Liu <lantaol@google.com>

vendor/k8s.io/utils/README.md

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+# Utils
+
+[![Build Status]](https://travis-ci.org/kubernetes/utils)
+
+A set of Go libraries that provide low-level,
+kubernetes-independent packages supplementing the [Go
+standard libs].
+
+## Purpose
+
+As Kubernetes grows and spins functionality out of its
+[core] and into cooperating repositories like
+[apiserver], [kubectl], [kubeadm], etc., the need
+arises for leaf repositories to house shared code and
+avoid cycles in repository relationships.
+
+This repository is intended to hold shared utilities
+with no Kubernetes dependence that may be of interest
+to any Go project.  See these [instructions for moving]
+an existing package to this repository.
+
+
+## Criteria for adding code here
+
+- Used by multiple Kubernetes repositories.
+
+- Full unit test coverage.
+
+- Go tools compliant (`go get`, `go test`, etc.).
+
+- Complex enough to be worth vendoring, rather than copying.
+
+- Stable, or backward compatible, API.
+
+- _No dependence on any Kubernetes repository_.
+
+## Libraries
+
+- [Exec](/exec) provides an interface for `os/exec`. It makes it easier
+  to mock and replace in tests, especially with
+  the [FakeExec](exec/testing/fake_exec.go) struct.
+
+[Build Status]: https://travis-ci.org/kubernetes/utils.svg?branch=master
+[Go standard libs]: https://golang.org/pkg/#stdlib
+[api]: https://github.com/kubernetes/api
+[apiserver]: https://github.com/kubernetes/apiserver
+[core]: https://github.com/kubernetes/kubernetes
+[ingress]: https://github.com/kubernetes/ingress
+[kubeadm]: https://github.com/kubernetes/kubeadm
+[kubectl]: https://github.com/kubernetes/kubectl
+[instructions for moving]: ./HOWTOMOVE.md