Update init files to register more app with the app registre app as well as the backup app

apps/checkouts/__init__.py

@@ -4,6 +4,7 @@ from django.utils.translation import ugettext_lazy as _
 
 from acls.api import class_permissions
 from app_registry import register_app, UnableToRegister
+from backups.api import AppBackup, ModelBackup
 from documents.models import Document
 from navigation.api import bind_links, register_top_menu
 from scheduler.api import LocalScheduler
@@ -42,6 +43,8 @@ checkouts_scheduler.start()
 initialize_document_checkout_extra_methods()
 
 try:
-    register_app('checkouts', _(u'Checkouts'))
+    app = register_app('checkouts', _(u'Checkouts'))
 except UnableToRegister:
     pass
+else:
+    AppBackup(app, [ModelBackup()])