Track downloads of extracts and downloads of source data for GA

[fgregg]

Add event code so that GA will track downloads of source data, and separately downloads of the new data extracts.

https://developers.google.com/analytics/devguides/collection/analyticsjs/events

[hancush]

There are already events for source data that should offer a good pattern for extracts.

[fgregg]

hmm.. this does not seem to be working, so the first thing to do is figure out why. when sam picks this up next week, i'll get him access to the GA site so he can check that out.

[fgregg]

@hancush pointed out that this event tracking is working, but is getting tracked in the main BGA site, not the salary subsection.