Use name given to command block instead of "@". Fixes BUKKIT-3803

By: Travis Watkins <amaranth@ubuntu.com>

paper-server/src/main/java/org/bukkit/craftbukkit/command/CraftBlockCommandSender.java

@@ -29,7 +29,7 @@ public class CraftBlockCommandSender extends ServerCommandSender implements Bloc
     }
 
     public String getName() {
-        return "@";
+        return commandBlock.getName();
     }
 
     public boolean isOp() {