Add endpoint for operational monitoring of server healt status

[petrkalina]

We could have a single health http endpoint without authentication that returns a 200 or 500 status matching general status and also returns a json doc with details.

Something like:

{
dicom: ok,
hl7: ok,
ui: ok,
db: ok,
storage space: warning 
}

[gunterze]

What's wrong with (still) using Nagios for that?

[petrkalina]

In case there is a load-balanced environment, it has to decide about the health of the archive services (dicom, hl7, http(s)). It is possible to do this indirectly via nagios, but this adds another dependency between the load-balancer and the archive. This would enable a simple uniform check that the load-balancers could use for all the archive endpoints. And the nagios could use this too!