title: Use vm.$on to listen to event emitted from child in vue.js 2.0
body: <p>I've been through the vue.js events section on events but it seems to only give examples of how to listen to events using the vm.$on handler within html.  Between that and the new changes for 2.0 I'm unsure how to simply transmit a event from child -> parent.</p>
  
  <p>I need to transmit an event because after parent receiving i want to broadcast it to another child.</p>
  
  <p>I'm using single page components, this is my setup:</p>
  
  <pre><code>// parent
  export default {
    mounted: function () {
      this.$on('myEvent', function (msg) {
      console.log('caught in parent', msg)
    });
   },
   components: {
    'child': child,
   },
  }
  
  // child
  this.$emit('myEvent', true)
  </code></pre>
  
  <p>How can I receive this event on the parent vm please?  Note, I don't want to use $on in the html.  I want the event receiving logic in the vm where it should be.</p>
  
  <p>Thanks,  </p>