Returns HTML for a single local action link.
$variables: An associative array containing:
function theme_menu_local_action($variables) {
$link = $variables['element']['#link'];
$link += array(
'href' => '',
'localized_options' => array(),
);
$link['localized_options']['attributes']['class'][] = 'button';
$link['localized_options']['attributes']['class'][] = 'add';
$output = '<li>';
$output .= l($link['title'], $link['href'], $link['localized_options']);
$output .= "</li>";
return $output;
}