Clean-up ames app

[cpsievert]

No description provided.

[rpodcast]

I ran the app (thanks @cpsievert for the heads up!) and everything works the way I envisioned. The only difference now is that any filtering conducted within the DT table (via the column filters client-side) will not subset the points that can be labelled. In the previous version, I was being too clever on giving the user an additional mechanism to prune the candidate points for labeling even further than the brushing itself. I'd say this is good to merge! I would like to keep using this example for further modules documentation and incorporate shinymeta functionality too.