eth2 quick update no. 5

Welcome to this week's eth2 quick update! tldr; Parity's Shasper joins Prysmatic's Sapphire testnet (the first public eth2 multi-client testnet)! Multiple eth2 block explorers launch -- Bitfly's beaconcha.in and Etherscan First eth2 networking call to tackle all the networkings -- Ben's notes and [Mamy's notes](https://gist.gi...