Support DHT-based IPNS routing over HTTP

[lidel]

part of #13

• Create IPIP that extends API introduced in IPIP-337 to support returning verifiable IPNS Record blobs
  • Key here is for client to be able to verify record themselves
  • This work is tracked in IPIP: Delegated IPNS over HTTP specs#343
• Implement support for it in someguy (backed by IPFS DHT+PubSub in the future)