Introduce a constant for the controller namespace

refs #5786

library/Icinga/Application/Web.php

@@ -307,7 +307,7 @@ class Web extends EmbeddedWeb
         $this
             ->getLoader()
             ->registerNamespace(
-                'Icinga\\Controllers',
+                'Icinga\\' . Dispatcher::CONTROLLER_NAMESPACE,
                 $this->getApplicationDir('controllers')
             )
             ->registerNamespace(

library/Icinga/Web/Controller/Dispatcher.php

@@ -18,6 +18,13 @@ use Zend_Controller_Response_Abstract;
  */
 class Dispatcher extends Zend_Controller_Dispatcher_Standard
 {
+    /**
+     * Controller namespace
+     *
+     * @var string
+     */
+    const CONTROLLER_NAMESPACE = 'Controller';
+
     /**
      * Dispatch request to a controller and action
      *
@@ -38,9 +45,10 @@ class Dispatcher extends Zend_Controller_Dispatcher_Standard
         }
         $controllerName = ucfirst($controllerName) . 'Controller';
         if ($this->_defaultModule === $this->_curModule) {
-            $controllerClass = 'Icinga\\Controllers\\' . $controllerName;
+            $controllerClass = 'Icinga\\' . self::CONTROLLER_NAMESPACE . '\\' . $controllerName;
         } else {
-            $controllerClass = 'Icinga\\Module\\' . $this->_curModule . '\\Controllers\\' . $controllerName;
+            $controllerClass = 'Icinga\\Module\\' . $this->_curModule . '\\' . self::CONTROLLER_NAMESPACE . '\\'
+                . $controllerName;
         }
         if (! class_exists($controllerClass)) {
             parent::dispatch($request, $response);