Flag images found at http://www.hahn-hotel.com/flags/
"All sets provided by us are free to use to anyone, for commercial or non-commercial websites."
18/06/2013: Serbian flag added from http://icondrawer.com/flag-icons.php (link added to plugin page)
11/08/2013: Montenegro flag added from http://icondrawer.com/flag-icons.php
06/09/2013: Georgian flag updated from http://icondrawer.com/flag-icons.php