Implement new endpoint microservices

[eperinan]

We need to create new endpoint which will return a list with all the microservices and nodes that the opscenter is monitoring.

In this issue we only are going to return a demo microservice with one node.

In the next sprint ... this endpoint will connect with Cassandra and will return the list with the results fetched from Cassandra.

@calvellido we have to deal with the structure of the message. This endpoint will return a string serialized with proto like as websocket as well.