Refresh the functions and returners.

def module_refresh(self, force_refresh=False, notify=False):
        '''
        Refresh the functions and returners.
        '''
        log.debug('Refreshing modules. Notify=%s', notify)
        self.functions, self.returners, _, self.executors = self._load_modules(force_refresh, notify=notify)

        self.schedule.functions = self.functions
        self.schedule.returners = self.returners