Load socket.io client lib from CDN

Based on user feedback, it was very non-obvious that if using an
web server other than multiplex/index.js it would be necessary to
upload the socket.io client libs. This negates that problem.

README.md

@@ -416,17 +416,16 @@ Reveal.initialize({
 	},
 
 	dependencies: [
-		{ src: 'socket.io/socket.io.js', async: true },
+		{ src: '//cdnjs.cloudflare.com/ajax/libs/socket.io/0.9.10/socket.io.min.js', async: true },
 		{ src: 'plugin/multiplex/client.js', async: true },
 		{ src: 'plugin/multiplex/master.js', async: true },
 	]
 });
 ```
 
-```multiplex.secret``` should only be configured on those pages you wish to be able to control slide navigatoin for all clients. Multi-master configurations work, but if you don't wish your audience to be able to control your slides, set the secret to null. In this master/slave setup, you should create a publicly accessible page with secret set to null, and a protected page containing your secret.
-
-You are very welcome to use the server running at reveal.jit.su, however availability and stability are not guaranteed. For anything mission critical I recommend you run your own server. It is simple to deploy to nodejitsu or run on your own environment.
+```multiplex.secret``` should only be configured on those pages you wish to be able to control slide navigation for all clients. Multi-master configurations work, but if you don't wish your audience to be able to control your slides, set the secret to null. In this master/slave setup, you should create a publicly accessible page with secret set to null, and a protected page containing your secret.
 
+You are very welcome to use the socketio server running at reveal.jit.su, however availability and stability are not guaranteed. For anything mission critical I recommend you run your own server. It is simple to deploy to nodejitsu or run on your own environment.
 
 ## Theming