Removed a redundant require_once file which doesn't exist

git-svn-id: http://framework.zend.com/svn/framework/standard/trunk@19817 44c647ce-9c0f-0410-b52a-842ac1e357ba

documentation/manual/en/module_specs/Zend_Feed_Pubsubhubbub-Introduction.xml

@@ -44,8 +44,7 @@
         
         <para>
             Perhaps surprisingly given its relative early age, Pubsubhubbub is already in use including
-            in Google Reader, Feedburner, Wordpress (plugins are availabe for self-hosted blogs), and
-            many more.
+            in Google Reader, Feedburner, and there are plugins available for Wordpress blogs.
         </para>
     </sect2>
 

library/Zend/Feed/Pubsubhubbub/Subscriber.php

@@ -17,8 +17,6 @@
  * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  */
- 
-require_once 'Zend/Feed/Pubsubhubbub/Entity/TopicSubscription.php';
 
 /**
  * @see Zend_Feed_Pubsubhubbub