Automatic merge from submit-queue

Add support for 3rd party objects to kubectl

@deads2k @jlowdermilk

Instructions for playing around with this:

Run an apiserver with third party resources turned on (`--runtime-config=extensions/v1beta1=true,extensions/v1beta1/thirdpartyresources=true`)

Then you should be able to:

```
kubectl create -f rsrc.json
```

```json
{
  "metadata": {
    "name": "foo.company.com"
  },
  "apiVersion": "extensions/v1beta1",
  "kind": "ThirdPartyResource",
  "versions": [
    {
      "apiGroup": "group",
      "name": "v1"
    },
    {
      "apiGroup": "group",
      "name": "v2"
    }
  ]
}
```

Once that is done, you should be able to:

```
curl http://<server>/apis/company.com/v1/foos
```

```
curl -X POST -d @${HOME}/foo.json http://localhost:8080/apis/company.com/v1/namespaces/default/foos
```

```json
{
  "kind": "Foo",
  "apiVersion": "company.com/v1",
  "metadata": {
    "name": "baz"
  },
  "someField": "hello world",
  "otherField": 1
}
```

After this PR, you can do:

```
kubectl create -f foo.json
```

```
kubectl get foos
```

etc.