Bootstrap button menu on wordpress

The following should setup your menu with the correct classes and IDs applied to your container and ul. The codex entry for wp_nav_menu lists all the possible arguments.

wp_nav_menu( array( 
    'theme_location' => 'primary', 
    'container_class' => 'menu-menu-container', 
    'menu_id' => 'menu-menu', 
    'menu_class' => 'btn-group' 
) );

You can then add the required classes to the menu items by using the nav_menu_css_class filter.

function my_special_nav_class( $classes, $item ) {
    $classes[] = 'btn btn-default';
    return $classes;
}
add_filter( 'nav_menu_css_class', 'my_special_nav_class', 10, 2 );