pricetracker data update

PL added 4/14 to 4/17
Merge remote-tracking branch 'origin/gh-pages'
DA adding 4/21-25 prices via webapp

couldn't add data via desktop GitHub application
Merging DA's pricetracker updates & conflict resolution

There was a conflict that needed to be resolved in order to merge this
change. For future reference:
http://gerrydevstory.com/2013/06/19/merging-git-conflicts-on-github/