title: Can't open select2 after init
body: <p>On <code>select2 4.0.2</code>, right after I init select2, I try to do : </p>
  
  <pre><code>$(myelement).select2("open") 
  </code></pre>
  
  <p>and I have this error : </p>
  
  <blockquote>
    <p>The select2('open') method was called on an element that is not using Select2</p>
  </blockquote>