We need a disk full threshold on the master that can stop the queue.

It is all too easy for a Jenkins deployment to fill up disk space on the master and have jobs fail or get stuck in unpredictable ways.  The jobs keep coming, making matters worse, and require human time to investigate.

We already have a threshold that will take slaves offline, and it appears there is an advisory that will pop up an alert on the admin console if the master is low on disk space, but we also need an emergency action when storage is critical.

Please add an option for a disk space threshold that will stop the Jenkins queue when storage on the master is critical.