MAGETWO-63154: Special characters in store name converted to numerical character references in email subject

(cherry picked from commit e89d09d)

Author: Andrewb89

lib/internal/Magento/Framework/Mail/Template/TransportBuilder.php

@@ -273,7 +273,7 @@ protected function prepareMessage()
         $body = $template->processTemplate();
         $this->message->setMessageType($types[$template->getType()])
             ->setBody($body)
-            ->setSubject($template->getSubject());
+            ->setSubject(html_entity_decode($template->getSubject(), ENT_QUOTES));
 
         return $this;
     }