Adding a way to run the upgrade script as a background daemon.
Adding a way to run the upgrade script as a background daemon.

This will allow the agent to call the upgrade script and be shutdown
without stopping the upgrade process.

enStratus/unix-agent,enStratus/unix-agent,enStratus/unix-agent,buzztroll/unix-agent,JPWKU/unix-agent,buzztroll/unix-agent,JPWKU/unix-agent,JPWKU/unix-agent,JPWKU/unix-agent,enStratus/unix-agent,buzztroll/unix-agent,buzztroll/unix-agent