Add ERROR as possible job status
Add ERROR as possible job status

If a job fails, its status is set to 'ERROR'. BTW that state is not
included in the list of available statuses ($availableJStatus).

MichaelMaar/concrete5,MichaelMaar/concrete5,avdevs/concrete5,matt9mg/concrete5,TimDix/concrete5,matt9mg/concrete5,MichaelMaar/concrete5,matt9mg/concrete5,avdevs/concrete5,avdevs/concrete5,TimDix/concrete5,TimDix/concrete5