Store the user items selection on cookie

This PR is related to issue #20 and it's working in progress because I need create tests.

![fm-store-user-selection-on-cookie](https://cloud.githubusercontent.com/assets/1503773/5240038/d22f5c08-78e0-11e4-8211-df980d113047.gif)
It's work with ```hidden_fields``` with default pattern ```resources```.
In the case of variant class I needed alter the default ```:url``` form because it's called from twice controllers.
Only with this ```<%= form_for :races, url: params[:controller].to_sym do |f| %>``` works. In this case the ```.to_sym``` becomes necessary to called routes from routes.rb.

What do you think?