Adding missing URI parameters (#229)

'_source_exclude' and '_source_include' was missing in parameters whitelist.

Author: Mantas Urnieža

Diff for: src/Search.php

@@ -663,6 +663,8 @@ public function addUriParam($name, $value)
             'lenient',
             'explain',
             '_source',
+            '_source_exclude',
+            '_source_include',
             'stored_fields',
             'sort',
             'track_scores',