Add Metrics class to start collecting data.

Signed-off-by: Staartvin <mijnleraar@msn.com>
Start collecting data when server is started.
Return error message when data is not being collected.

Signed-off-by: Staartvin <mijnleraar@msn.com>
Add Metrics dependency and repository.

Signed-off-by: Staartvin <mijnleraar@msn.com>