Add JobACL to monitor console to see jobs

Looks like before the status command did not limit the
view of jobs according to the JobACL.

As the ACLs now have been fixed, we need to allow the
monitor ressource to see all jobs because otherwise
we see nothing.

Fixes #378: Bareos tray monitor - not accurate information from
bareos-dir
Fix compiler warnings in btape
Fix removing of supplemental groups.

When we add bareos to the right supplemental groups we should use
the -a option of usermod so it leaves the other supplemental groups
alone.

Fixes #382: Don't remove supplemental groups on install.