Added ping and duck, showing category in trivia.

src/games/ping.js

@@ -0,0 +1,10 @@
+'use strict';
+
+function onCommand(args, context) {
+	context.sendMessage(`Pong, @${context.user.username}!`, context.room.id);
+}
+
+module.exports = {
+	name: 'Ping',
+	onCommand,
+};