Improve reliability of DHT invites

• make multiserver-dht@5.0.0-rc and ssb-dht-invite@2.0.0-rc
• proof of concept phone-to-phone replication over UTP
• try to use hyperswarm
• when dht server code has been claimed by remote peer, dont show it in the UI as staged
• reattempt handshakes until it works, with exponential backoff
• sbot-gossip should reconnect to previously-connected dht peers
• test with real friends