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.
The trends view should access to the modelAttribute, which could be a good field to pass back.  I don't think this implementation deviates from what we currently have though:

```
track('edx.bi.csv.downloaded', {
  courseId: 'sample/course/id',
  label: 'enrollment_activity',
  type: 'click',
  category: 'trend'
}, {});
```

When multiple CSVs are downloadable on the page, we'll need to augment those too.