Test backup rotation if backup job passes midnight

[ccztux]

Nothing more to say...

[ccztux]

It could be an issue, when backup_rotation_one_backup_per_day_only is activated and the backup job is sometimes ready before midnight and sometimes after midnight. Actually the timestamps necessary for rotation will be generated after backup in the function: rotateHandler and his helper functions. We will change this, so that the timestamps, which are necessary to check if the backup files should be rotated, or not will be generated at script startup.