Strip unused columns from csv files loaded by visualizations

[colinmorris]

Minimal subset looks like it should be:

artist,track,Year,energy,liveness,tempo,speechiness,acousticness,instrumentalness,valence,danceability,mean_energy,mean_liveness,mean_tempo,mean_speechiness,mean_acousticness,mean_instrumentalness,mean_valence,mean_danceability

[colinmorris]

Done.