Refactoring

I have some refactoring to suggest. I have som point to clarify

 - If you have specs, it can be very very useful. 
 - Is it one of your goal be compatible with old rails versions? Why do you write `render(:partial => "...", :locals => "...")` instead of `render(partial: "..", "...")` and why do you use the old ruby synthax?

It think `app/views/smart_listing/item/_create.js.rb` can be simplified. It can be simpler and clearer than : 

    <%= smart_listing_item :create, object: resource,
      partial: resource.valid? ? "item" : "form" %>