Fix link registratio from menu to tool

apps/maintenance/registry.py

@@ -0,0 +1,12 @@
+from __future__ import absolute_import
+
+from django.utils.translation import ugettext_lazy as _
+
+from .icons import icon_maintenance_menu
+from .links import maintenance_menu
+
+label = _(u'Maintenance')
+description = _(u'Central registration and execution of app maintenance code.')
+icon = icon_maintenance_menu
+dependencies = ['navigation', 'icons', 'permissions']
+tool_links = [maintenance_menu]