Add VuFindSearch event namespace

* VuFindSearch/Service.php (setEventManager): Add `VuFindSearch' event
namespace, following common zf2 pattern.

module/VuFindSearch/src/VuFindSearch/Service.php

@@ -244,10 +244,11 @@ class Service
      * @param EventManagerInterface $events Event manager
      *
      * @return void
+     * @todo   Deprecate `VuFind\Search' event namespace (2.2)
      */
     public function setEventManager(EventManagerInterface $events)
     {
-        $events->setIdentifiers('VuFind\Search');
+        $events->setIdentifiers(array('VuFind\Search', 'VuFindSearch'));
         $this->events = $events;
     }