core: before sending out a job new/change/removal message, send out unit change messa...

core: before sending out a job new/change/removal message, send out unit change message for job's unit

We always want the state of the unit to be reflected first to the
client before we claim the job has changed state, after all the job is
the request to change unit state, and thus job changes are kinda the
confirmation that the state changed as requested.