Use collections.abc.Iterable instead of collections.Iterable

The latter is going to be removed after Python 3.8

settings.py

@@ -24,10 +24,33 @@ INSTALLED_APPS = (
     'django.contrib.auth',
     'django.contrib.contenttypes',
     'django.contrib.admin',
+    'django.contrib.messages',
     'localized_fields',
     'tests',
 )
 
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+            ],
+        },
+    },
+]
+
+MIDDLEWARE = [
+    'django.contrib.messages.middleware.MessageMiddleware',
+    'django.contrib.sessions.middleware.SessionMiddleware',
+    'django.contrib.auth.middleware.AuthenticationMiddleware',
+]
+
 # set to a lower number than the default, since
 # we want the tests to be fast, default is 100
 LOCALIZED_FIELDS_MAX_RETRIES = 3