cookie images and disable CSRF protection in create action (user and sessions)

more info

image in js --> 
http://stackoverflow.com/questions/7381041/url-of-images-in-javascript-code-using-rails-3-1-asset-pipeline

disable CSRF protection -->
http://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection/ClassMethods.html
http://stackoverflow.com/questions/23377648/cant-verify-csrf-token-authenticity-rails-4-1