Creates a .htaccess file in each Drupal files directory if it is missing.
function file_ensure_htaccess() {
file_save_htaccess('public://', FALSE);
if (variable_get('file_private_path', FALSE)) {
file_save_htaccess('private://', TRUE);
}
file_save_htaccess('temporary://', TRUE);
file_save_htaccess(config_get_config_directory(), TRUE);
}