[names] Reponse time in results

[re1]

To improve performance optimization and also for clients to show expected loading times, a queries response time could be returned with the queries results or saved to a database for client to retrieve the response time from the last query before sending a new request.

[re1]

At the moment only timestamps of the queries retrieval are saved in the web service cache database. This database will have to be extended to store the last response time.

It might also be a good idea to provide an interface for getting a response time only. This feature needs further investigation.