Add support for "Get local service health"

[superflav]

Being able to get a service's aggregated health status on a given node by service_name or service_id at the following endpoints is super useful, but not currently supported in python-consul2. Would be a great addition to this library.

/agent/health/service/name/:service_name
/agent/health/service/id/:service_id

Consul documentation on these endpoints:

https://www.consul.io/api-docs/agent/service#get-local-service-health

[poppyred]

@superflav Thank you for your issues. I will check and implement all the new functions as soon as possible.

[monkeyman192]

I am just looking at needing this kind of functionality as well.
I realised it can be hacked by doing something like c.http.get(CB.json(), path='/v1/agent/health/service/name/XXX'), however it's very hacky, and this request also raises a 503 when one of the services is down...
Anyway, adding a +1 to wanting this functionality!