Upgrade to Rails 4

Traditionally, hcking always upgraded really early to new versions of Rails. I think, we should to it again with Rails 4 :wink: In my opinion, if we update now to RC1, we can after that start the heavy refactoring and then adding new features.

What do you think?

Resources:

* [Railscast: Upgrading to Rails 4](http://railscasts.com/episodes/415-upgrading-to-rails-4)
* [Railscast: What's new in Rails 4](http://railscasts.com/episodes/400-what-s-new-in-rails-4)
* [Rails 4 Zombie Outlaws](http://rails4.codeschool.com/videos)
* [Strong Params as Documentation](http://robots.thoughtbot.com/post/49374573556/strong-parameters-as-documentation)