Add a timeline section to the bottom of the student view.

Review Request #7258 — Created April 28, 2015 and submitted — Latest diff uploaded




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.