title: component's onchange event not triggered
body: <p>I'm guessing that this might be intentional but couldn't find mention in the docs. (If it's intentional, I'll make a PR to clarify the docs).</p>
  
  <p>ref: <a href="http://jsfiddle.net/2ce9c0r4/8/" rel="nofollow">this jsfiddle</a></p>
  
  <p>my html:</p>
  
  <pre><code>&lt;div id='container'/&gt;
  </code></pre>
  
  <p>and my javascript:</p>
  
  <pre><code>Person = Ractive.extend({
    template : '&lt;p&gt;{{name}}&lt;/p&gt;',
    onchange : function(obj){console.log(obj)}
  })
  
  flintstones = new Ractive({
    el : '#container',
    template : "{{#names}}&lt;person/&gt;{{/}}",
    data : {names : [{id:1, name:"Fred"},{id: 2, name:"Barney"}]},
    components : {person : Person}
  })
  </code></pre>
  
  <p>if I make a data change in the component with:</p>
  
  <pre><code>flintstones.findAllComponents('person')[1].set('name','Wilma')
  </code></pre>
  
  <p>there is no 'onchange' event logged to the console. However if the flintstones Ractive instance is configured with an 'onchange' handler, then setting the data in the component is logged.</p>
  
  <p>Intentional or bug or am I doing something wrong here?</p>