Update Folders and Document apps to use the latest backup classes definitions

apps/folders/__init__.py

@@ -7,6 +7,7 @@ from navigation.api import (bind_links, register_top_menu,
 from documents.models import Document
 from acls.api import class_permissions
 from acls.permissions import ACLS_EDIT_ACL, ACLS_VIEW_ACL
+from backups.api import AppBackup, ElementBackupModel
 
 from .models import Folder
 from .links import (folder_list, folder_create, folder_edit,
@@ -42,3 +43,5 @@ class_permissions(Document, [
     PERMISSION_FOLDER_ADD_DOCUMENT,
     PERMISSION_FOLDER_REMOVE_DOCUMENT,
 ])
+
+AppBackup('folders', _(u'Folders'), [ElementBackupModel()])