Landing page event carousels

Added a carousel for events on the landing page with tabs: upcoming and past.

Notes:

Carousels will show the 28 most recent events in total.
On page load, the upcoming events tab will be selected by default. If there are no upcoming events, the past events carousel will be selected instead.
All events filtering is on a day basis; time is not considered. This means:
- Events starting and ending on the same day are moved to the past events carousel a day after the event start date. E.g an event occurring Nov 4th will remain in the upcoming events carousel for the whole day, even if the event finished earlier that day.
- If an event spans multiple days, the event will remain in upcoming events until it concludes.
An event is highlighted if it's occurring within the next 7 days (again, time is not considered).

Before

After

ubccsss / ubccsss.org