Round 1 / drand: distributed, verifiable randomness

Thanks to drand stability and stewardship, the League of Entropy was able to operate with a 100% uptime during the entire period covered by this RetroPGF round, furthermore the drand maintainers have been operating 3 "drand relays" to guarantee that SPs can access the randomness produced by the League of Entropy with as little latency as possible, allowing them to start computing any required proofs as soon as they need to.