title: Vue directive is being triggered for other components that were not affected
body: <p>I have a directive:</p>
  
  <pre><code>Vue.directive('autosave', {
      componentUpdated(el) {
          console.log(el);
      },
  })
  </code></pre>
  
  <p>I have 2 elements (vuetify):</p>
  
  <pre><code>this is a wrapper around input
  &lt;v-text-field label="Field 1" v-model="model1" v-autosave&gt;&lt;/v-text-field&gt;
  &lt;v-text-field label="Field 2" v-model="model2" v-autosave&gt;&lt;/v-text-field&gt;
  </code></pre>
  
  <p>If I make a change to the first input, the directive for BOTH get called. Why is this? How can I make it so only the affected element is called?</p>
  
  <p>Vue version: 2.5.3<br>
  Vuetify version: 1.0.0-beta.4</p>