Criado um wrapper para quem não possui a app django-maintenancemode instalada.

sigi/middleware.py

@@ -0,0 +1,9 @@
+try:
+    # try use maintenancemode middleware from django-maintenancemode project
+    import maintenancemode.middleware
+    class MaintenanceModeMiddleware(maintenancemode.middleware.MaintenanceModeMiddleware):
+        pass
+except ImportError:
+    # otherwise, a thin wrapper for middleware
+    class MaintenanceModeMiddleware(object):
+        pass

sigi/settings.py

@@ -64,7 +64,7 @@ MIDDLEWARE_CLASSES = (
     'django.middleware.gzip.GZipMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.contrib.auth.middleware.AuthenticationMiddleware',
-    'maintenancemode.middleware.MaintenanceModeMiddleware',
+    'sigi.middleware.MaintenanceModeMiddleware',
     'django.middleware.cache.CacheMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.doc.XViewMiddleware',