feat(core): remove the (^ syntax and make all DOM events bubbling

BREAKING CHANGE

Before
<div (^click)="onEventHandler()">
  <button></button>
</div>

After
<div (click)="onEventHandler()">
  <button></button>
</div>

Closes #3864

modules/angular2_material/src/components/checkbox/checkbox.html

@@ -1,6 +1,6 @@
 <style>@import "package:angular2_material/src/components/checkbox/checkbox.css";</style>
 
-<div (^click)="toggle($event)">
+<div (click)="toggle($event)">
   <div class="md-checkbox-container">
     <div class="md-checkbox-icon"></div>
   </div>