minor inprovements and included organizations in changelog

app/models/admin_ability.rb

@@ -208,7 +208,7 @@ class AdminAbility
     end
 
     can [:index, :revert_object, :revert_attribute], PaperTrail::Version,
-        item_type: %w(Event EventType Track DifficultyLevel EmailSettings Room Cfp Program Comment), conference_id: conf_ids_for_cfp
+        item_type: %w[Event EventType Track DifficultyLevel EmailSettings Room Cfp Program Comment], conference_id: conf_ids_for_cfp
     can [:index, :revert_object, :revert_attribute], PaperTrail::Version,
         ["item_type = 'Commercial' AND conference_id IN (?) AND (object LIKE '%Event%' OR object_changes LIKE '%Event%')", conf_ids_for_cfp] do |version|
       version.item_type == 'Commercial' && conf_ids_for_cfp.include?(version.conference_id) &&

app/models/conference.rb

@@ -760,6 +760,10 @@ class Conference < ActiveRecord::Base
     self
   end
 
+  def to_param
+    short_title
+  end
+
   private
 
   # Returns a different html colour for every i and consecutive colors are

app/models/organization.rb

@@ -1,6 +1,8 @@
 class Organization < ActiveRecord::Base
   resourcify :roles, dependent: :delete_all
 
+  has_paper_trail
+
   has_many :conferences, dependent: :destroy
 
   after_create :create_roles