title: on-change doesn't work on v-select
body: <p>I tried to use a v-select who display all countries. so i did : </p>
  
  <pre><code>&lt;v-select on-change="updateCountryId" label="country_name" :options="countries" &gt;&lt;/v-select&gt;
  </code></pre>
  
  <p>it works great and display my countries but the function updateCountryId doesn't seems to work </p>
  
  <pre><code>methods: {
      updateCountryId: function() {
          alert('ok');
      }
  }
  </code></pre>
  
  <p>but i never see the ok</p>
  
  <p>to import vue-select I did :</p>
  
  <pre><code>&lt;script src="/js/vue-select/vue-select.js"&gt; &lt;/script&gt;
  </code></pre>
  
  <p>i use it in a twig file so in my vue-select.js i rewrite what i found on <a href="https://unpkg.com/vue-select@1.3.3" rel="noreferrer">https://unpkg.com/vue-select@1.3.3</a> but replace the {{ }} by &lt;% %></p>
  
  <p>ps : i already tried v-on:change, @change and onChange</p>
  
  <p>and my code looks like that (i skip thing i judge useless)</p>
  
  <pre><code>&lt;div id="General"&gt;
  &lt;div class="form-group"&gt;
    &lt;label&gt;Pays :&lt;/label&gt;
      &lt;v-select  onChange="updateCountryId" label="country_name" :options="countries" &gt;&lt;/v-select&gt;
  &lt;/div&gt;
  .
  .
  .
  &lt;script src="/js/vue-select/vue-select.js"&gt; &lt;/script&gt;
  &lt;script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/vue/1.0.13/vue.min.js"&gt;&lt;/script&gt;
  &lt;script&gt;
    Vue.config.delimiters = ['&lt;%', '%&gt;'];
    Vue.component('v-select', VueSelect.VueSelect);
    var vm = new Vue({
      el: "#General",
      data: {
          countries: [],
      }, 
      filters: {
      },
      methods: {
          updateCountryId: function () {
              console.log('ok');
              alert('ok');
           },`
  </code></pre>