cronjobs, re #2793
- fix filtering for non-Firefox-browsers
- disable bulk button unless an action is selected
- remove red marker for selected task when editing a schedule
- fix datepicker and timepicker bug in chrome/webkit by declaring inputs as 'text' instead of 'date' or 'time'


git-svn-id: svn://develop.studip.de/studip/trunk@25620 c5b85792-5220-0410-ad23-ed5b6b8ad999
cronjobs: add js documentation, refines [25620], re #2793

git-svn-id: svn://develop.studip.de/studip/trunk@25621 c5b85792-5220-0410-ad23-ed5b6b8ad999