Convenience: flag for just returning jobid or json

[kristinriebe]

I'd like to have a flag that suppresses any other output and just returns the id of a newly created job after sending a new job request. I.e. something like:
uws --host https://www.cosmosim.org/uws/query --user <...> --password <...> job new query='...' table='...' --returnjobid
shall return only the jobid, or an error if no job was created.
As it is now, a script using the uws-client would need to parse the output first to find the job id.
Alternatively, we could also return the job parameters as json if a --json flag is set.

Or would you suggest another "hook", maybe importing UWS as a module in a Python script and then use the more basic functions when writing scripts for sending many jobs at once?