Double-check that RAA adds up at a team level

This is worth thinking about:

https://twitter.com/tangotiger/status/605172517553082368

I think that `RAA` will add up, across categories, for each team, but it's worth double-checking.

The way to do this would be to re-write `getRAA()` so that you can group at the team level. Or better yet, have `getRAA()` accept an argument that would be passed to `dplyr::group_by()`. This would actually be pretty useful. Not sure how tricky this would be...