number of MaxJobs exceeded: should be "warning"

[ms at psa-systeme.de]

When cups rejects jobs due to the total number of active jobs is exceeding the "MaxJobs" value there is only an "information" being printet into error_log.

But in fact it can be absolutely desasterous if jobs are rejected and nobody has a chance to notice. So at least this incident should be worth a "warning" in error_log. I do consider if it was worth an alert to the system admin.