Allow health check endpoints to be access via plain http

In particular we're interested in allowing local health checks with consul without the need to configure TLS in the consul agent, but it also addresses the fact that the instructions in our health check documentation don't work for omnibus installations (when you try curl localhost/-/health you get a 404. You can do curl -k https://localhost/-/health, with -k to avoid SSL verification, but for other clients, like consul in our case, it's not that simple)

Not sure if:

• This is the best approach
• This should be behind a feature flag
• This should specify the three endpoints (/-/health, /-/readiness, /-/liveness) instead of the current rule (/-/) – I'm relying on the monitoring whitelist for security here.

* Latest changes address those last two