Implemented api end points for interacting with demultiplex jobs

- This is WIP, I have mainly focused on the api end points, the actual functionality in sisyphusmaster has not been sufficiently addressed
- Made some changes to execution of sisyphus (wrapped in future etc.), I'm open for a discussion on that :smile: 
I really like both of these TODOs. I think it's critical not to block the actor here if we want to be able to abort the Sisyphus run by a message from the master.