[Errors] Provide clear messages about Elasticsearch status when running the server

[dvsrepo]

I don't know where is the best place but I would like to have a very clear message when some starts the server and the Elasticsearch endpoint is not available/running, etc, I don't know if we check that at some point but I recall the message it's a standard trace. We should be very informative at this point, explaining:

We checked the elastic search endpoint at {ES_URL} and is not responding/available..
Please make sure your Elasticsearch is running, or (check the user roles config) <- whatever message it makes sense.
Ideally this should be applicable to other scenarios when the ES instance is not responding --> including a trace in the server process.

I think this is key to help our users troubleshoot the issues with Elastic which is frequently the only bottleneck for getting started.

[frascuchon]

We must keep in mind that this kind of info about error should be available ONLY at server startup. Returning detailed info about elasticsearch status or error details could compromise the infrastructure security and is not recommended at all