Octopus now has running field in JobStatus.
Also add running field to JobStatusResponse.

Increased test coverage of JobStatusResponse.
The state string is scheduler specific so we can't tell when job is done by using only the state string.
Whether job is done can be determined from isDone() and getException() of JobStatus instance.
Send jsonified status object to callback.

Do not serialize exception as it gives to much information, just return exception message.