function san_add_taxonomies_to_pages() {

    register_taxonomy_for_object_type( 'post_tag', 'page' );

    register_taxonomy_for_object_type( 'category', 'page' );

    }

    add_action( 'init', 'san_add_taxonomies_to_pages' );

    if ( ! is_admin() ) {

    add_action( 'pre_get_posts', 'san_category_and_tag_archives' );

    }

    function san_category_and_tag_archives( $wp_query ) {

    $my_san_post_array = array('post','page');

    if ( $wp_query->get( 'category_name' ) || $wp_query->get( 'cat' ) )

    $wp_query->set( 'post_type', $my_san_post_array );

    if ( $wp_query->get( 'tag' ) )

    $wp_query->set( 'post_type', $my_san_post_array );

    }