Add rateLimit event (#2019)

* add ratelimited event

* add some useful props

* death

* more death

* Update tester1000.js

* Update RequestHandler.js

test/tester1000.js

@@ -10,6 +10,7 @@ client.on('debug', log);
 client.on('ready', () => {
   log('READY', client.user.tag, client.user.id);
 });
+client.on('rateLimit', log);
 
 const commands = {
   eval: message => {