Automatic merge from submit-queue
Support sort-by timestamp in kubectl get
## Pull Request Guidelines
1. Please read our [contributor guidelines](https://github.com/kubernetes/kubernetes/blob/master/CONTRIBUTING.md).
1. See our [developer guide](https://github.com/kubernetes/kubernetes/blob/master/docs/devel/development.md).
1. Follow the instructions for [labeling and writing a release note for this PR](https://github.com/kubernetes/kubernetes/blob/master/docs/devel/pull-requests.md#release-notes) in the block below.
```release-note
```
**Before:**
```console
$ kubectl get svc --sort-by='{.metadata.creationTimestamp}'
proto: no encoder for TypeMeta unversioned.TypeMeta [GetProperties]
proto: tag has too few fields: "-"
proto: no coders for struct *reflect.rtype
proto: no encoder for sec int64 [GetProperties]
proto: no encoder for nsec int32 [GetProperties]
proto: no encoder for loc *time.Location [GetProperties]
proto: no encoder for Time time.Time [GetProperties]
proto: no coders for intstr.Type
proto: no encoder for Type intstr.Type [GetProperties]
F0513 16:46:49.499894 29562 sorting_printer.go:182] Field {.metadata.creationTimestamp} in TypeMeta:<kind:"Service" apiVersion:"v1" > metadata:<name:"kubernetes" generateName:"" namespace:"default" selfLink:"/api/v1/namespaces/default/services/kubernetes" uid:"b88b4739-1964-11e6-9ac3-64510658e388" resourceVersion:"8" generation:0 creationTimestamp:<2016-05-13T16:45:06-07:00> labels:<key:"component" value:"apiserver" > labels:<key:"provider" value:"kubernetes" > > spec:<ports:<name:"https" protocol:"TCP" port:443 targetPort:<type:0 intVal:443 strVal:"" > nodePort:0 > clusterIP:"10.0.0.1" type:"ClusterIP" sessionAffinity:"ClientIP" loadBalancerIP:"" > status:<loadBalancer:<> > is an unsortable type: struct, err: unsortable type: struct
```
**After:**
```console
$ kubectl get svc --sort-by='{.metadata.creationTimestamp}'
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes 10.0.0.1 <none> 443/TCP 48s
frontend 10.0.0.108 <none> 80/TCP 10s
```
@kubernetes/kubectl
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