alternate redis failure implementation of all() for pyres

# pyres/failure/redis.py

    @classmethod
    def all(cls, resq, start=0, count=1):
        items = resq.redis.lrange('resque:failed', start, count) or []
        ret_list = []
        for i in items:
            failure = ResQ.decode(i)
            failure['redis_value'] = base64.b64encode(i)
            ret_list.append(failure)
        return ret_list