Add Reindex endpoing

* add reindex function
* fix namespace and comment for reindex api

src/Elasticsearch/Client.php

@@ -807,6 +807,33 @@ public function index($params)
         return $endpoint->resultOrFuture($response);
     }
 
+    /**
+     * $params['refresh']             = (boolean) Should the effected indexes be refreshed?
+     *        ['timeout']             = (time) Time each individual bulk request should wait for shards that are unavailable
+     *        ['consistency']         = (enum) Explicit write consistency setting for the operation
+     *        ['wait_for_completion'] = (boolean) Should the request should block until the reindex is complete
+     *        ['requests_per_second'] = (float) The throttle for this request in sub-requests per second. 0 means set no throttle
+     *        ['body']                = (array) The search definition using the Query DSL and the prototype for the index request (Required)
+     *
+     * @param $params array Associative array of parameters
+     *
+     * @return array
+     */
+    public function reindex($params)
+    {
+        $body = $this->extractArgument($params, 'body');
+
+        /** @var callback $endpointBuilder */
+        $endpointBuilder = $this->endpoints;
+        /** @var \Elasticsearch\Endpoints\Reindex $endpoint */
+        $endpoint = $endpointBuilder('Reindex');
+        $endpoint->setBody($body);
+        $endpoint->setParams($params);
+        $response = $endpoint->performRequest();
+
+        return $endpoint->resultOrFuture($response);
+    }
+
     /**
      * $params['index']          = (list) A comma-separated list of index names to restrict the operation; use `_all` or empty string to perform the operation on all indices
      *        ['ignore_indices'] = (enum) When performed on multiple indices, allows to ignore `missing` ones

src/Elasticsearch/Endpoints/Reindex.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Elasticsearch\Endpoints;
+
+/**
+ * Class Reindex
+ *
+ * @category Elasticsearch
+ * @package  Elasticsearch\Endpoints\Indices
+ * @author   Augustin Husson <husson.augustin@gmail.com>
+ * @license  http://www.apache.org/licenses/LICENSE-2.0 Apache2
+ * @link     http://elasticsearch.org
+ */
+class Reindex extends AbstractEndpoint
+{
+
+    /**
+     * @return string[]
+     */
+    protected function getParamWhitelist()
+    {
+        return array(
+            'refresh',
+            'timeout',
+            'consistency',
+            'wait_for_completion',
+            'requests_per_second',
+        );
+    }
+
+    /**
+     * @return string
+     */
+    protected function getURI()
+    {
+        return '/_reindex';
+    }
+
+    /**
+     * @return string
+     */
+    protected function getMethod()
+    {
+        return 'POST';
+    }
+
+    /**
+     * @param array $body
+     *
+     * @throws \Elasticsearch\Common\Exceptions\InvalidArgumentException
+     * @return $this
+     */
+    public function setBody($body)
+    {
+        if (isset($body) !== true) {
+            return $this;
+        }
+
+        $this->body = $body;
+
+        return $this;
+    }
+}