Update homepage design

[davepeck]

Let's make it two sections, one for upcoming, and one for past meetings.

Each section should have a small paragraph of text summarizing all the meetings shown on the calendar, followed by a relatively compact calendar display.

In the upcoming calendar view, we will show all scheduled meetings, whether or not they have summarizable content. It should be clear at a glance when a summary is available, and easy to dig into it.