Undefined object(s) set on FormModel when using select2 with ajax

[zosnap]

This is due to an underlying issue with how stickit handles option tags, see: nytimes/backbone.stickit#285

I don't expect that issue to get resolved anytime soon since I don't think that project is maintained, so it would be nice to fix this in Torso. @mandragorn suggested setting it up as a view-level or field-level override, so you can choose whether to allow the fallback to checking the option value directly.

For reference, here is the stickit getVal method for select elements: https://github.com/nytimes/backbone.stickit/blob/master/backbone.stickit.js#L696

And here is how I've overridden and replaced that:

let selectHandler = _.find(Backbone.Stickit._handlers,(h) => {
  return h.selector === 'select';
});
selectHandler.getVal = function($el) {
  var selected = $el.find('option:selected');

  if ($el.prop('multiple')) {
    return _.map(selected, function(el) {
      let stickitVal = Backbone.$(el).data('stickit-bind-val');
      if (stickitVal !== undefined) {
        return stickitVal;
      } else {
        return Backbone.$(el).val();
      }
    });
  } else {
    let stickitVal = selected.data('stickit-bind-val');
    if (stickitVal !== undefined) {
      return stickitVal;
    } else {
      return selected.val();
    }
  }
};