public function gravatar($email, array $options = array(), array $attributes = array()) {
        $options = $options + array(
            'default' => 'mm',
            'size' => 80,
            'rating' => 'g',
            'hash' => 'md5',
            'secure' => env('HTTPS')
        );

        $email = Security::hash(strtolower(trim($email)), $options['hash']);
        $query = array();

        if ($options['secure']) {
            $image = 'https://secure.gravatar.com/avatar/' . $email;
        } else {
            $image = 'http://www.gravatar.com/avatar/' . $email;
        }

        foreach (array('default' => 'd', 'size' => 's', 'rating' => 'r') as $key => $param) {
            $query[] = $param . '=' . urlencode($options[$key]);
        }

        $image .= '?' . implode('&amp;', $query);

        return $this->Html->image($image, $attributes);
    }