This PR modfies the original 3-valued cron strings used in package schedule to be traditional 5-valued cron strings.
- schedule.Weekly will validate that the month and dom fields are equal to *
- cli autostart/autostop will attempt to detect local timezone using TZ env var, defaulting to UTC
- cli autostart/autostop no longer accepts a raw schedule -- instead use the --minute, --hour, --dow, and --tz arguments.
- Default schedules are provided that should suffice for most users.
Fixes#993
