Track additional events

The goal is to eventually add tracking for the following actions:

* Click the "help" button at the top of the page
* Hover over the "more info" icons

This is an early review so that I can get early directional feedback before investing too heavily in a particular approach.
Trend is too generic. Once we add enrollment modes, this view will most likely get used for more both enrollment and activity trends. Either the consuming view should pass the tracking category or you should infer it from the chart title or some other unique parameter.