Fix YouTube track data

Thank you sedmelluq#687

Author: thedarkcolour

main/src/main/java/com/sedmelluq/discord/lavaplayer/source/youtube/YoutubeTrackJsonData.java

@@ -29,6 +29,11 @@ public static YoutubeTrackJsonData fromMainResult(JsonBrowser result) {
       JsonBrowser playerInfo = NULL_BROWSER;
       JsonBrowser playerResponse = NULL_BROWSER;
 
+      if (result.isMap()) {
+          playerInfo = result.get("player");
+          playerResponse = result.get("playerResponse");
+      }
+
       for (JsonBrowser child : result.values()) {
         if (child.isMap()) {
           if (playerInfo.isNull()) {