Something like vipnode agent --health="localhost:8080/health"?

Things we want to include (probably as a JSON object):

• Status: OK or ERROR? (When is it in error state? E.g. if node is missing? What about block number lagging?)
• Block number (vs highest known block)
• ActivePeers
• Whitelisted peers (note: agents are stateless, so would only be whitelisted peers since the agent has started)

Anything else?