title: Error with i18n when i put a badge in appbar
body: <p>I a working with vuejs &amp; vuetify, when i put a badge in my appbar i recive a warning from i18n:</p>
  
  <p>vue-i18n.esm.js?a925:33 [vue-i18n] Value of key '$vuetify.badge' is not a string!</p>
  
  <p>vue-i18n.esm.js?a925:33 [vue-i18n] Cannot translate the value of keypath '$vuetify.badge'. Use the value of keypath as default.</p>
  
  <pre><code>&lt;template&gt;
      &lt;v-btn class="ml-2" min-width="0" text v-bind="attrs" v-on="on"&gt;
        &lt;v-badge color="red" overlap bordered&gt;
          &lt;template v-slot:badge&gt;
            &lt;span&gt;5&lt;/span&gt;
          &lt;/template&gt;
  
          &lt;v-icon&gt;mdi-bell&lt;/v-icon&gt;
        &lt;/v-badge&gt;
      &lt;/v-btn&gt;
  &lt;/template&gt;
  </code></pre>
  
  <p>It has happened to someone or someone knows how to deal with it</p>
  
  <p>Thanks:</p>
  
  <p>Jose Rodriguez</p>