nuages/settings.py: fix django 1.4 compatibility

nuages/settings.py

@@ -4,6 +4,7 @@
 import os
 import socket
 from django.conf import global_settings
+import django
 
 DEBUG = False
 TEMPLATE_DEBUG = DEBUG
@@ -31,7 +32,8 @@ DATABASES = {
 
 ACCOUNT_ACTIVATION_DAYS = 7  # Activation window
 
-TEST_RUNNER = 'django.test.runner.DiscoverRunner'
+if django.VERSION >= (1, 6):
+    TEST_RUNNER = 'django.test.runner.DiscoverRunner'
 
 # Local time zone for this installation. Choices can be found here:
 # http://en.wikipedia.org/wiki/List_of_tz_zones_by_name