Add prefix to job name

The jobname created by tge_make follows a specific rule and distinction by qstat could be difficult when independent jobs are submitted by tge_make. We can distinguish with the path when full jobnames are examined. However, qstat prints only the first 10 charactors of the job name and when all are make_20140 it is not distinguishable.  This patch allows to add a user-specified string before the automatic jobnames so that the user is easier to monitor the status of independent jobs.