This warning appear's because you have the lines:
require_once 'Zend/Loader.php';
Zend_Loader::registerAutoload();
Replace them with
require_once 'Zend/Loader/Autoloader.php';
$loader = Zend_Loader_Autoloader::getInstance();
$loader->registerNamespace('App_');
Where 'App_' is the name of a directory on your include path that has
classes within it that follow the Zend Framework naming convention, so
change it as appropriate and add more if you need them.