Maintaining the runtime directories

It would be good to clean up the runtime directories occasionally. In particular:

Archive these log files:

• /tmp/pbs/working/server_logs/* on the server node
• /tmp/pbs/working/server_priv/accounting/* on the server node
• /tmp/pbs/working/sched_logs/* on the scheduler node
• /tmp/pbs/working/mom_logs/* on every MOM node

Remove old junk from:

• /tmp/pbs/working/spool/* on every MOM node
• /tmp/pbs/working/undelivered/* on every MOM node
• /tmp/pbs/working/mom_priv/jobs/* on every MOM node
• /tmp/pbs/working/server_priv/jobs/* on the server node