Rest: remove status code from main action

Today we give the HTTP status back within the HTTP response itself and within the JSON response as well:

```sh
curl localhost:9200/
```

```js
{
  "status" : 200,
  "name" : "Red Wolf",
  "version" : {
    "number" : "2.0.0",
    "build_hash" : "6837a61d8a646a2ac7dc8da1ab3c4ab85d60882d",
    "build_timestamp" : "2014-08-19T13:55:56Z",
    "build_snapshot" : true,
    "lucene_version" : "4.9"
  },
  "tagline" : "You Know, for Search"
}
```

We can remove the `status` in elasticsearch 2.0.