changes from comments, fix commercials failing test

db/migrate/20140730104658_migrate_roles_for_can_can.rb

@@ -1,28 +0,0 @@
-class MigrateRolesForCanCan < ActiveRecord::Migration
-
-  def up
-    # Store the number of existing roles
-    old_roles = Role.count
-
-    Role.all.each do |role|
-      role.users.each do |user|
-        Conference.all.each do |conference|
-          if role.name == 'Admin' || role.name == 'Organizer'
-            user.add_role :organizer, conference
-          else
-            user.add_role role.name.parameterize.underscore.to_sym, conference
-          end
-        end
-      end
-    end
-
-    # Delete old roles
-    Role.first(old_roles).each do |role|
-      role.destroy
-    end
-  end
-
-  def down
-    raise ActiveRecord::IrreversibleMigration.new('Cannot reverse migration. Deleted events cannot be re-created')
-  end
-end