Add ability to view whether scheduled tasks are running in UI

[tom114]

Describe your idea for a new feature

Administrators should be able to view when IRIDA's scheduled tasks are running through the UI to verify the services are still updating. We should have some system that shows either when the most recent run was (and possibly its result) or when the most recent last # of runs happened.

Describe how you would access this feature?

Probably through the admin panel. Possibly on the admin statistics page.

Additional information

This would be very useful to help learn if/when some of the scheduled tasks have failed. Ex: NCBI uploads failing, emails failing to send, sync jobs not launching.