.

* move helper methods (except current_user) into the controller and/or the model
  * move first into the controller then refactor into the model where appropriate
* read http://guides.rubyonrails.org/association_basics.html
  * look into aliases
      * <code>:source</code> and <code>:class_name</code> and <code>:foreign_key</code>
  * look into <code>:include</code>
  * look into <code>:dependent => :destroy</code>