Implement Admin commands for APS Scheduler.

[ninadicara]

• Admin command to create a schedule
• Admin command to set start and end of API calls.
• Admin command to delete a schedule (and associated schedules).

[ninadicara]

Uncertain whether it is possible to stop the scheduler from the admin.
Alternative might be to have an admin action that deletes all the upcoming jobs - this is doable by calling all the job names.