Migrate Crowbar framework to Rails 4.0

Migrate Crowbar framework to Rails 4.0
    
This pull request migrates the Crowbar framework to being a Rails 4 web app, and does some cleanup along the way.
    
* Model-based access control (via attr_accessible and attr_protected)
  has been replaced with strong parameter based access control See
  http://guides.rubyonrails.org/action_controller_overview.html#strong-parameters
  for more information on how to use strong parameters. All of our
  models and controllers have been updated to use strong parameters.
* render_error in the application_controller knows how to turn
  ActiveRecord::RecordNotFound exceptions into proper 404 errors, and
  ActiveRecord::RecordInvalid exceptions into 409 errors.  The
  find_key model helper now just adds the model and key we were
  searching for to the RecordNotFound exception if it cannot find the
  object we are looking for.
* find_key has been replaced with find_by wherever applicable when it
  was being called from within a model.  You should now only use
  find_key from within a controller.
* The api_foo methods in application_controller.rb have been
  simplified to rely on render_error catching and handling errors they
  may throw.
* Rails no longer allows you to abuse STI the way we have been doing
  in the past.  The barclamp import process now handles creating
  specialized roles, attributes, and jigs.