Remove list from wordpress nav, replace with span

gistfile1.aw

<p class="menu-main-menu-container">
	<?php wp_nav_menu( array( 'menu' => 'Main Menu','container' => false,'items_wrap' => '%3$s','walker' => new no_list_custom_nav_walker() ) ); ?>
</p>


class no_list_custom_nav_walker extends Walker {
    var $tree_type = array( 'post_type', 'taxonomy', 'custom' );
    var $db_fields = array( 'parent' => 'menu_item_parent', 'id' => 'db_id' );
    function start_lvl(&$output, $depth) {
        $indent = str_repeat("\t", $depth);
        $output .= "\n$indent<ul class=\"sub-menu\">\n";
    }
    function end_lvl(&$output, $depth) {
        $indent = str_repeat("\t", $depth);
        $output .= "$indent</ul>\n";
    }
    function start_el(&$output, $item, $depth, $args) {
        global $wp_query;
        $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';
        $class_names = $value = '';
        $classes = empty( $item->classes ) ? array() : (array) $item->classes;
        $classes = in_array( 'current-menu-item', $classes ) ? array( 'current-menu-item' ) : array();
        $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
        $class_names = strlen( trim( $class_names ) ) > 0 ? ' class="' . esc_attr( $class_names ) . '"' : '';
		$attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
        $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
        $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
        $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';
        $item_output = $args->before;
        $item_output .= "<a". $attributes . $class_names .'>';
        $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
        $item_output .= "</a> ";
        $item_output .= $args->after;
        $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
    function end_el(&$output, $item, $depth) {}
}