'Warn if any socket_host is \'localhost\'. See #711.'

def check_localhost(self):

    for (k, v) in cherrypy.config.items():
        if ((k == 'server.socket_host') and (v == 'localhost')):
            warnings.warn("The    use    of    'localhost'    as    a    socket    host    can    cause    problems    on    newer    systems,    since    'localhost'    can    map    to    either    an    IPv4    or    an    IPv6    address.    You    should    use    '127.0.0.1'    or    '[::1]'    instead.")
