Generate run_status.json on the fly

[DavidGoldwasser]

Currently when I run a scenario run_status.json is generated after the scenario is finished. As I'm checking on progress of a scenario run now, I have to step through each feature directory under run looking to see if an out.osw has been generated, and then in that OSW to see if it failed or not. It would be great if run_status.json could be used as a way to more easily monitor a run. I know some feedback comes across the console log, but I have some cases where I'm running multiple scenarios as once (splitting my computer resources across them), so it is harder to keep up with the console output.