title: Table sorted date not correct
body: <p>Expected:
  I'll get a datetime string from an API returned. This value <code>"2019-08-15T15:58:14.597Z"</code> should be displayed in a table as `DD-MM-YYYY HH:MM.
  Vuetify comes with a data table component, that can sort the data ascending and descending. I also want to use this functionality for the date, to make it sort ascending and descending.</p>
  
  <p>Short question: The date from the API should be saved and displayed in another "style" in the table, but the sort-functionality uses the real date object.</p>
  
  <p>My current code:</p>
  
  <pre><code>&lt;template&gt;
      &lt;v-content class="mt-12 ml-12"&gt;
          &lt;h1 class="font-weight-black display-3"&gt;Servers&lt;/h1&gt;
  
          &lt;v-data-table
              class="elevation-1"
              :headers="headers"
              :items="columns"
              :items-per-page="15"
          &gt;
          &lt;/v-data-table&gt;
  
          &lt;ul id="example-1"&gt;
              &lt;li v-for="(data, index) in columns.data" :key="index"&gt;
                  {{ data.attributes }}
              &lt;/li&gt;
          &lt;/ul&gt;
      &lt;/v-content&gt;
  &lt;/template&gt;
  
  &lt;script&gt;
  import instances from '../services/instances';
  
  export default {
    data() {
      return {
        columns: [],
        headers: [
          { text: 'Server Name', value: 'attributes.name' },
          { text: 'Spieler', value: 'attributes.playerCount' },
          { text: 'Avg. FPS', value: 'attributes.details.rust_fps_avg' },
          { text: 'Wiped', value: 'attributes.details.rust_last_wipe' },
        ],
      };
    },
    async created() {
      const { data } = await instances.createInstance();
      this.columns = data.data;
      this.columns.forEach((entry) =&gt; {
        const { players, maxPlayers } = entry.attributes;
        entry.attributes.playerCount = `${players} / ${maxPlayers}`;
        const { rust_last_wipe } = entry.attributes.details;
        const mmmm = new Date(entry.attributes.details.rust_last_wipe);
        entry.attributes.details.rust_last_wipe = `${mmmm.getDate()}.${mmmm.getMonth() + 1}.${mmmm.getFullYear()}`;
      });
      console.log(this.columns);
    },
  };
  &lt;/script&gt;
  </code></pre>