A BackgroundRunner plugin instance will stop running
(rescheduling a check every 2 seconds) when there is no
(or no more) job to run.
Clients of this service now have to emit an event after
adding a job into PluginShare.backgroundJobs, so an
already loaded but stopped BackgroundRunner can notice
it and start running again.
* Use getCapacityHW() to ensure latest battery capacity can be retrieved
* BackgroundRunner
* Start background_runner_spec.lua
* AutofrontLight plugin now uses BackgroundRunner plugin