public function put($key, $value, $ns = 'conf')
 {
     $configurationManager = new Configuration();
     if (isset($this->confTab[$ns][$key])) {
         $configurationManager->change(array('value' => $value), array('key' => $ns . ':' . $key));
     } else {
         $configurationManager->add($key, $value, $ns);
     }
     $this->confTab[$ns][$key] = $value;
     unset($_SESSION['configuration']);
 }