Missing ending newline in bulk payload

Hi,

It seems an ending newline is needed when creating the bulk payload (http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/docs-bulk.html).

For example, when I index three documents with the bulk api, the last document is not indexed :

```
<?php
require_once __DIR__ . '/vendor/autoload.php';

use \ElasticSearch\Client;
$es = Client::connection('http://127.0.0.1:9200/myindex/mytype');
$documents = array();
$documents['doc1'] = array('title' => 'My bulked entry 1');
$documents['doc2'] = array('title' => 'My bulked entry 2');
$documents['doc3'] = array('title' => 'My bulked entry 3');


$es->beginBulk();
foreach ($documents as $id => $document) {
    echo "Indexing document $id\n";
    $es->index($document, $id);
}
$es->commitBulk();
```

Only the first two documents are indexed :

    curl -XGET 'http://127.0.0.1:9200/myindex/mytype/_search?pretty=true'

```
{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 2,
    "max_score" : 1.0,
    "hits" : [ {
      "_index" : "myindex",
      "_type" : "mytype",
      "_id" : "doc1",
      "_score" : 1.0, "_source" : {"title":"My bulked entry 1"}
    }, {
      "_index" : "myindex",
      "_type" : "mytype",
      "_id" : "doc2",
      "_score" : 1.0, "_source" : {"title":"My bulked entry 2"}
    } ]
  }
}
```

Expected result :
```
{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 3,
    "max_score" : 1.0,
    "hits" : [ {
      "_index" : "myindex",
      "_type" : "mytype",
      "_id" : "doc1",
      "_score" : 1.0, "_source" : {"title":"My bulked entry 1"}
    }, {
      "_index" : "myindex",
      "_type" : "mytype",
      "_id" : "doc2",
      "_score" : 1.0, "_source" : {"title":"My bulked entry 2"}
    }, {
      "_index" : "myindex",
      "_type" : "mytype",
      "_id" : "doc3",
      "_score" : 1.0, "_source" : {"title":"My bulked entry 3"}
    } ]
  }
}
```