Add this to functions.php

// Pick out the version number from scripts and styles
function remove_version_from_style_js( $src ) {
    if ( strpos( $src, 'ver=' . get_bloginfo( 'version' ) ) )
        $src = remove_query_arg( 'ver', $src );
    return $src;
}
add_filter( 'style_loader_src', 'remove_version_from_style_js');
add_filter( 'script_loader_src', 'remove_version_from_style_js');