title: How does Buefy datepicker output 'yyyy-MM-dd' string?
body: <p>I have a date picker in my Buefy form in my Vue application that is suppose to populates a table from an api call. I populate the api call with the Buefy form. 
  the api call needs the format 'yyyy-MM-dd' but i receive a totally different format from buefy <code>v-model="startdate"</code>. </p>
  
  <p>I am passing the startdate into the api call as of <code>${this.startdate}</code>.
  I need it to be a string in the format 'yyyy-MM-dd'.
  example date string: '2019-04-23'</p>
  
  <p>how do I achieve this? is it possible with the date-parser property of buefy datepicker ? if so what would the function be? </p>
  
  <p>so far I have <code>:date-parser="dateParser"</code> in the b-datepicker tag</p>
  
  <p>and in the methods i have </p>
  
  <pre><code>dateParser(date) {
        new Date.parse(date);
      }
  </code></pre>
  
  <p>whats next?</p>