@staticmethod
    def _clean_backend_config(config):

        return dict([
            (key.lower(), val)
            for key, val in config.iteritems()
        ])
Return ``config`` (a dict) with the keys downcased. (This is
dataset/ETHPy150Open rapidsms/rapidsms-core-dev/lib/rapidsms/router.py/Router._clean_backend_config