Timeout per measurement

[jimaek]

Lets add a new standardized optional global parameter to all measurement types. Something like timeout: Seconds

• It would change the timeout per test type by changing the parameters we pass to the tools on the probe side
• Each test must exit cleanly without zombie processes being stuck. e.g. if I set a timeout of 10s and the server takes 50s to respond, the process on the probe must exit at 10s or be killed and the API must return "finished".
• Return appropriate errors when timeouts are hit