createItem = function(option, data) {
  data = data || option;
  var elementData =  {
    class: "selectr-option",
    role: "treeitem",
    "aria-selected": false
  };

  if(this.customOption){
    elementData.html = this.config.renderOption(data); // asume xss prevention in custom render function
  } else{
    elementData.textContent = option.textContent; // treat all as plain text
  }
  var opt = util.createElement("li",elementData);


  opt.idx = option.idx;

  this.items.push(opt);

  if (option.defaultSelected) {
    this.defaultSelected.push(option.idx);
  }

  if (option.disabled) {
    opt.disabled = true;
    util.addClass(opt, "disabled");
  }

  return opt;
}
Build a list item from the HTMLOptionElement
@param  {int} i      HTMLOptionElement index
@param  {HTMLOptionElement} option
@param  {bool} group  Has parent optgroup
@return {void}