Check the actual whitelist for Player#isWhitelisted()

The server's check is for whether or not a player can pass the whitelist
not just if the player is on it. That seems like more useful information
but the API has always just checked if they are on it so this commit
restores that.

src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -752,7 +752,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
 
     @Override
     public boolean isWhitelisted() {
-        return server.getHandle().isWhitelisted(getProfile());
+        return server.getHandle().getWhitelist().isWhitelisted(getProfile());
     }
 
     @Override