add 'plugins' config option, new way of registering es5 plugins

demo.html

@@ -429,7 +429,7 @@ Reveal.on( 'customevent', function() {
 				transition: 'slide', // none/fade/slide/convex/concave/zoom
 
 				// More info https://github.com/hakimel/reveal.js#dependencies
-				dependencies: [ Zoom, Notes, Search, Markdown, Highlight ]
+				plugins: [ Zoom, Notes, Search, Markdown, Highlight ]
 			});
 
 			deck.initialize();