[Plugin: JSON API] optimization for get_page_index

Hello there,
thanks for your great API.
I have a small optimization.
Introduced an aditional option “exclude_content” that, if true, prevents to send the content. This helps reducing the load if you just only need the page hierarchy.
Hope it helps.

public function get_page_index() {
    global $json_api;
    extract($json_api->query->get(array('exclude_content')));
    $pages = array();
    // Thanks to blinder for the fix!
    $numberposts = empty($json_api->query->count) ? -1 : $json_api->query->count;
    $wp_posts = get_posts(array(
      'post_type' => 'page',
      'post_parent' => 0,
      'order' => 'ASC',
      'orderby' => 'menu_order',
      'numberposts' => $numberposts
    ));
    foreach ($wp_posts as $wp_post) {
      $page = new JSON_API_Post($wp_post);
      if($exclude_content) {
        $page->set_value('content', '');
      }
      $pages[] = $page;
    }
    foreach ($pages as $page) {
      $json_api->introspector->attach_child_posts($page);
    }
    return array(
      'pages' => $pages
    );
  }