Update this-chart.js

Commented out lines 117 and 306 to fix a Chrome version 29.0.1547.65 display issue. The bingo piece would not show up when you clicked on a square and the entire square would disappear. Now, the text will remain and the piece will appear beneath the text.
Added instructions on changing hashtags for Twitter shares

- In live_files/js/this-chart.js, on line 147, change the "hashtags=debatebingo" parameter in the URL to "hashtags=emmysbingo" or whatever hashtag you want to use for the event. In the live_files/embed.html on line 156, update the hashtag #debatebingo to your new hashtag for this card.
Merge pull request #2 from DFMdata/master

Chrome bug fix, more docs