* [ADDED] new monitoring method : endCronjob
* [IMPROVED] Use newly added error codes
* [ADDED] mail notifications, enabled by default
* [ADDED] cron disable on fatal errors with exit code != 0
* [ADDED] Command line swtich: -f = Force running crons even if disabled
* [ADDED] Disabled status in monitoring site
This will improve error handling in our cronjobs. Fatal errors now
require manual intervention by explicityly running crons with the force
option (`-f`). Until they are forced to run, crons will stay disabled.
Fixes#773 once merged