/**
  * create a category
  *
  * @param string $name
  * @param string $description
  * @return \Category
  */
 public function createCategory($name, $description)
 {
     // array to send the model corectly
     $content = array('name' => $name, 'description' => $description);
     list($this->last_result, $this->last_error) = $this->rest_client->post($this->path, $content);
     $this->erreur = $this->getError($this->last_result, $this->last_error);
     if (isset($this->erreur)) {
         return null;
     }
     if (!Category::isJsonValid($this->last_result)) {
         $this->erreur = $this->jsonErrorMessage();
         return null;
     }
     return new Category($this->last_result);
 }