With the volume of students this term, we've had some difficultly checking in

whether students are doing weekly code drops. This change adds a new section to

the student view that has a timeline of events. At the moment, this shows when

new review requests are posted, and when an update to a review request that

includes a new diff is posted.
As part of this, I ended up refactoring the calendar in the main view to be a

reusable element which automatically sorts its entries in the right order.

Looked at lots of different students and saw the expected timelines.