Dump counters to file

def _dump_cnt(self):
        '''Dump counters to file'''
        self._cnt['1h'].dump(os.path.join(self.data_path, 'scheduler.1h'))
        self._cnt['1d'].dump(os.path.join(self.data_path, 'scheduler.1d'))
        self._cnt['all'].dump(os.path.join(self.data_path, 'scheduler.all'))