Do not purge batch files at completion time

Do not purge the script and environment files for completed jobs on
slurmctld reconfiguration or restart (they might be later requeued).
Purge the files only when the job record is purged.
bug 834
Update commit 02263d8f40ce.
scontrol now accepts the option job=xxx or jobid=xxx for the
requeue, requeuehold and release operations.
Merge remote-tracking branch 'origin/slurm-14.03'