Move Cron functions to CronLib

Also, wire up lots of the UI to the backend and create a UI for editing
and creating new schedules. Schedule editor shows the projected runtimes
for the job, etc. Create schema for events
in the database. Change how the admin page shows things.
Add means to enable/disable schedules

Because it's kinda an important feature. SO now there's just an int
flag with each event marking if it's enabled or disabled.
Add the enabled status to the schedules view

So it's easy to see, at a glance, what's enabled and disabled.
Make the schedule editor have an enabled checkbox

And have that enabled box reflect the real value in the db