Merge pull request #109 from ScottDowne/t1164

[#1164] wmode for youtube iframe player.

players/youtube/popcorn.youtube.js

@@ -10,7 +10,7 @@ window.onYouTubePlayerAPIReady = function() {
 // existing youtube references can break us.
 // remove it and use the one we can trust.
 if ( window.YT ) {
-  window.quarantineYT = window.YT
+  window.quarantineYT = window.YT;
   window.YT = null;
 }
 
@@ -244,6 +244,8 @@ Popcorn.player( "youtube", {
       options.youtubeObject = new YT.Player( container.id, {
         height: height,
         width: width,
+        wmode: "transparent",
+        playerVars: { wmode: "transparent" },
         videoId: src,
         events: {
           "onReady": function(){