Added cron protection to stop PHP scripts being able to get outside of the user's home directory but added an open_basedir directive to the crontab script line entries, this fixes bug #532 and bug number #370. Also added another dropdown option to the list of timings, so now users can also request a cron job runs monthly as requested in bug #531. (previously longest time period was weekly.) Needs full testing however as I cannot access a ZPanel test install from work however from my local CLI testing it was working great but need to test with the full complexities of a production ZPanel installation.