Adapted user to run cron-jobs for the victor agent

Hi all,

this pull request fixes issue #11 . It changes the user which runs the cron-job for the victor agent from root to cmspopdb. This user is configurable via the $DASHBUSER variable.
It might be useful to specify a common variable, which sets the user, for all configurations. Currently some configurations use the $POPDBUSER variable (xrootd and crab) and others use the $DASHBUSER variable (victor agent, popdb.web and popdb.cmssw).

Please feel free to comment.

Cheers, Rene