Disable pages indexation in Drupal (meta robots=noindex)

template.php

<?php

/**
 * Implements hook_preprocess_html().
 */
function <theme>_preprocess_html(&$vars)
{
    $meta = array(
        '#tag' => 'meta',
        '#attributes' => array(
            'name'    => 'robots',
            'content' => 'noindex, nofollow',
        ),
    );
    drupal_add_html_head($meta, 'robots');
}