rails4: adding css compressor in production.

reference: https://github.com/alindeman/upgradingtorails4
rails4: fixing first issues that occur when opening the page in a browser using rails server.

* Replaceing some finder methods.
* Replacing a reorder method.
* For some reason, I had to deactivate the horizontal nav for the moment, since it has caused the server to hang up.

Further help in upgrading to rails 4, including an overview of the new features:

* http://railscasts.com/episodes/415-upgrading-to-rails-4
* http://guides.rubyonrails.org/4_0_release_notes.html
* http://guides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-3-2-to-rails-4-0

Trello: https://trello.com/c/Dlio0wG9/281-rails-4