Quit fetcher

def quit(self):
        '''Quit fetcher'''
        self._running = False
        self._quit = True
        self.ioloop.add_callback(self.ioloop.stop)
        if hasattr(self, 'xmlrpc_server'):
            self.xmlrpc_ioloop.add_callback(self.xmlrpc_server.stop)
            self.xmlrpc_ioloop.add_callback(self.xmlrpc_ioloop.stop)