* improve libp2p connected peer metrics
* separate discv5 port from libp2p for NAT open
* use metric family for DISCOVERY_BYTES
* Merge branch 'unstable' of https://github.com/sigp/lighthouse into improve-metrics
This PR adds some health endpoints for the beacon node and the validator client.
Specifically it adds the endpoint:
`/lighthouse/ui/health`
These are not entirely stable yet. But provide a base for modification for our UI.
These also may have issues with various platforms and may need modification.
