Proposal: add jobs with limited runs

[smarques]

Hi, thank you for this library.
I am considering using this to build a 'sequencer' for OSC calls.
To fit my use case, I would need to add some jobs that run at a given interval but also to set a limit to the number of runs.
So I created a job class extending SimpleIntervalJob that accepts an extra option with the number of runs and just stops after the nth run.
I suppose there would be other ways to achieve this, but I couldn't figure them out :)
Maybe this is outside the use case of this library, but if you are interested in a PR let me know!

Thank you again

[kibertoad]

@smarques Sounds good! Would you be open to send a PR for this?