Support for Lighthouse v0.3.0+

[MysticRyuujin]

Looks like Lighthouse changed their HTTP API
sigp/lighthouse#1434

I think that it now breaks the eth2stats-client

WARN Error processing HTTP API request method: GET, path: /beacon/head, status: 405 Method Not Allowed, elapsed: 271.068µs

[protolambda]

Planning to fix this shortly. Was hoping the existing v1 (standard api) beacon type option would work, but there I also experienced some incompatibility. Have a v0.3 lighthouse node up to test against, fix shouldn't take too long. Thanks for opening this issue 👍

[protolambda]

run  --eth2stats.node-name="test123"   --eth2stats.addr="grpc.zinken.eth2.wtf:8080" --eth2stats.tls=false      --beacon.type="v1" --beacon.addr="http://127.0.0.1:5052"  --beacon.metrics-addr="http://127.0.0.1:5054/metrics"

Try this