This change adds the beginnings of the administration mode which is available

to mentors. This mode is entered by clicking a "Manage" toggle at the top-right

of the page.
This mode is currently implemented for the Calendar page. Switching into manage

mode will show all of the events (even ones in the past), and some additional

UI. Each event can be edited or deleted, and new events can be added.

Added, edited, and deleted calendar items. Toggled to manage mode a bunch.