Add easter egg to only play closed PRs

To use this, just set `ULTIMATE_DREAM_KILLER` in your DevTools console.

The explanation for this easter egg is can be found in this article[1].
Just look for `Ultimate Dream Killers`. Some people just like to see
other people's dreams crushed 👎

[1] https://blog.jessfraz.com/post/the-art-of-closing/

app/public/js/main.js

@@ -93,6 +93,10 @@ function isEventInQueue(event){
  * To extend this function, simply add return true for events that should be filtered.
  */
 function shouldEventBeIgnored(event){
+  // This adds an easter egg to only play closed PRs
+  if (!!ULTIMATE_DREAM_KILLER)
+    return (event.type !== "PullRequestEvent" || event.action !== "closed");
+
   return false;
 }