Fix button trait type. Closes #3497

src/trait_manager/view/TraitButtonView.js

@@ -2,12 +2,14 @@ import { isString } from 'underscore';
 import TraitView from './TraitView';
 
 export default TraitView.extend({
-  events: {
+  eventCapture: ['click button'],
-    'click button': 'handleClick'
-  },
 
   templateInput: '',
 
+  onChange() {
+    this.handleClick();
+  },
+
   handleClick() {
     const { model, em } = this;
     const command = model.get('command');