Expire the reqid generated by http_gate

[miketang84]

The results calculated by other nodes of the blockchain network, couldn't be consumed by their own http_gate instance, so we need a mechanism to expire those keys in the redis cache.

On the other side, even if the same http_gate and spin_worker, if http_gate was broken, the key will leave there forever, so we also need to expire them after some time.

Feel that 3 minutes is a good trade-off right now.