Update jquery.nestable.js

[mean-cj]

fix dd-handle on sub parents has been a problem

<li class="dd-item">
  <div class="dd3-content">
   <div class='text'></div>
   <div class='dd-handle'></div>
  </div>
<li>

[tchapi]

FWIW I've created a more active fork here and included your fix amongst others ;)