fix for invalid GET /_aliases route. (#663)

* fix for new /_alias instead of /_aliases

* No longer a valid endpoint

https://github.com/elastic/elasticsearch/tree/6.x/rest-api-spec/src/main/resources/rest-api-spec/api

* remove invalid route.

Author: Artistan

src/Elasticsearch/Endpoints/Indices/Aliases/Get.php

@@ -914,8 +914,8 @@ public function getAliases($params = array())
         /** @var callback $endpointBuilder */
         $endpointBuilder = $this->endpoints;
 
-        /** @var \Elasticsearch\Endpoints\Indices\Aliases\Get $endpoint */
-        $endpoint = $endpointBuilder('Indices\Aliases\Get');
+        /** @var \Elasticsearch\Endpoints\Indices\Alias\Get $endpoint */
+        $endpoint = $endpointBuilder('Indices\Alias\Get');
         $endpoint->setIndex($index)
                  ->setName($name);
         $endpoint->setParams($params);