Add `component:update:components` event, allows listen to inner components changes. Closes #1409

src/dom_components/model/Component.js

@@ -162,9 +162,9 @@ const Component = Backbone.Model.extend(Styleable).extend(
       this.set('status', '');
 
       // Register global updates for collection properties
-      ['classes', 'traits'].forEach(name =>
-        this.listenTo(this.get(name), 'add remove change', () =>
-          this.emitUpdate(name)
+      ['classes', 'traits', 'components'].forEach(name =>
+        this.listenTo(this.get(name), 'add remove change', (...args) =>
+          this.emitUpdate(name, ...args)
         )
       );
       this.init();
@@ -877,10 +877,10 @@ const Component = Backbone.Model.extend(Styleable).extend(
       return scr;
     },
 
-    emitUpdate(property) {
+    emitUpdate(property, ...args) {
       const em = this.em;
       const event = 'component:update' + (property ? `:${property}` : '');
-      em && em.trigger(event, this);
+      em && em.trigger(event, this, ...args);
     },
 
     /**