Extends the CMR Rest API to support inspectIT app servers test

Extend the inspectIT REST API so that is possible to get information about the status of the CMR and how many agents are connected to the CMR. In addition add possibility to get information about the last data sent from the agent..

This REST API extension is needed to test the functionality of inspectIT automatically on different app servers (based on the Simon Becker bachelor thesis​).

Will be assigned to as he was Simon's supervisor.