title: Vuetify datepicker apears without event icon and with blank fields
body: <p>I have a Vuetify datepicker and when I run the code it appears without the event icon (it appears wit the letters "event") and when I open the datepicker the days appear in blank. It gives no error on the console.
  Image:
  <a href="https://pasteboard.co/HV7eD1O.png" rel="nofollow noreferrer">https://pasteboard.co/HV7eD1O.png</a></p>
  
  <pre><code>&lt;v-flex xs12 sm6 md4&gt;
      &lt;v-dialog ref="dialog" v-model="modal" :return-value.sync="date" persistent lazy full-width width="290px"&gt;
        &lt;v-text-field slot="activator" v-model="date" label="Picker in dialog" prepend-icon="event"readonly&gt;
        &lt;/v-text-field&gt;
        &lt;v-date-picker v-model="date" scrollable&gt;
          &lt;v-spacer&gt;&lt;/v-spacer&gt;
          &lt;v-btn flat color="primary" @click="modal = false"&gt;Cancel&lt;/v-btn&gt;
          &lt;v-btn flat color="primary" @click="$refs.dialog.save(date)"&gt;OK&lt;/v-btn&gt;
        &lt;/v-date-picker&gt;
      &lt;/v-dialog&gt;
    &lt;/v-flex&gt;
  
  export default {
    data() {
      return {
        book: {
          title: null,
          subtitle: null,
          authors: null,
          publishDate: null,
          nrPages: null,
          publisher: null,
          language: null,
          thumbnailUrl : null
        },
        date: new Date().toISOString().substr(0, 10),
        modal: false,
        error: null,
        success: null,
        dialog: false,
        datepicker : false,
        required: (value) =&gt; !!value || 'Required.'
      }
    },
  </code></pre>