app_settings: use new app_settings pattern

portail_citoyen/app_settings.py

@@ -1,5 +1,20 @@
-from django.conf import settings
+import sys
 
-TEMPLATE_VARS = getattr(settings, 'PORTAIL_CITOYEN_TEMPLATE_VARS', {})
-FAVICON_URL = getattr(settings, 'PORTAIL_CITOYEN_FAVICON_URL', 'http://www.entrouvert.com/favicon.ico')
-WCSINST_DEFAULT_VARIABLES = getattr(settings, 'PORTAIL_CITOYEN_WCSINST_DEFAULT_VARIABLES', {})
+class AppSettings(object):
+    __defaults = {
+            'TEMPLATE_VARS': {},
+            'FAVICON_URL': 'http://www.entrouvert.com/favicon.ico',
+            'WCSINST_DEFAULT_VARIABLES':  {},
+    }
+
+    __prefix = 'PORTAIL_CITOYEN_'
+
+    def __getattr__(self, name):
+        from django.conf import settings
+        if name not in self.__defaults:
+            raise AttributeError
+        return getattr(settings, self.__prefix + name, self.__defaults[name])
+
+app_settings = AppSettings()
+app_settings.__name__ = __name__
+sys.modules[__name__] = app_settings