Drupal n-level submenus working with Zurb Foundation 5

template.php

/**
* This snippet should replace the old 'zurb_foundation_links__system_main_menu' found on template.php inside the zurb-foundation theme
/*

/**
 * Implements theme_links() targeting the main menu specifically
 * Outputs Foundation Nav bar http://foundation.zurb.com/docs/navigation.php
 *
 */
function zurb_foundation_links__system_main_menu($vars) {
    // Get all the main menu links
    $menu_links = menu_tree_output(menu_tree_all_data('main-menu'));

    // Initialize some variables to prevent errors
    $output = '';
    $output .= recursive_menu($menu_links);

    return '<ul class="left">' . $output . '</ul>';
}

function recursive_menu($menu_links)
{
    $output = '';
    $sub_menu = '';

    foreach ($menu_links as $key => $link) {
        if (!empty($link['#href'])) {
            $classes = 'class="'.(!empty($link['#below']) ? $link['#attributes']['class'][] = 'has-dropdown' : '').'"';
            $output .= '<li ' . $classes . '>' . l($link['#title'], $link['#href']);

            if (!empty($link['#below']))
            {
                $output .= !empty($link['#below']) ? '<ul class="dropdown">' . recursive_menu($link['#below']) . '</ul>' : '';
            }

            $output .= '</li>';
        }
    }

    unset($sub_menu);
    $sub_menu = '';
    return $output;
}