Use sti_name instead of model_class in migration

Author: amaierhofer

db/migrate/20150915120219_add_people_contact_data_visible.rb

@@ -7,7 +7,7 @@
 
 class AddPeopleContactDataVisible < ActiveRecord::Migration[4.2]
   def change
-    types = Role.all_types.select { |r| r.permissions.include?(:contact_data) }
+    types = Role.all_types.select { |r| r.permissions.include?(:contact_data) }.map(&:sti_name)
     Person.where(id: Role.where(type: types).select(:person_id)).update_all(contact_data_visible: true)
   end
 end