Allow adding, editing, and deleting events.

[smenjas]

So far, the calendar is a static entity. It only shows dates, but doesn't allow scheduling. Let's change that.

Scope: For the first iteration, allow assigning events to a given day. Assigning start and end times with finer granularity could be something to save for later. It's more important to get events addition, editing, and deletion working than it is to assign start and end times.

We don't need to make it fancy yet. We don't have to allow marking them complete, or inviting other people, or allowing multiple fields for each event. Just a title and a date is sufficient.

Keep in mind we want to show events on each of the views that exist so far:

• The monthly view must show at least whether any events exist that day.
• Ideally, Show a weekly view. #10 & Show a daily view. #11 would be implemented already, so we can show event details on those views.
• If there's a yearly view, we might just mark dates with a different shade or color if any events exist that day.

[smenjas]

Users can add events as of ab37aac, but cannot view them on calendars, edit them, or delete them yet.

[smenjas]

Users can edit events as of 508ed7f, but cannot delete them or see them on calendars yet.

[smenjas]

Users can see events on the monthly and daily views (see c74d212 & 652ef97 respectively).

[smenjas]

This is now a CRUD app! We can create, read, update, and delete events. There's plenty to be desired in terms of UX, but it's a start.