Enable and fix lint

tests/settings.py

@@ -1,10 +1,9 @@
 from __future__ import absolute_import, unicode_literals
 
 import os
-from pkg_resources import parse_version as V
 
 import django
-
+from pkg_resources import parse_version as V
 
 DATABASES = {
     'default': {
@@ -56,6 +55,7 @@ TEMPLATES = [
     },
 ]
 
+
 def get_middleware_settings():
     return (
         'django.middleware.common.CommonMiddleware',
@@ -69,6 +69,7 @@ def get_middleware_settings():
         'wagtail.wagtailcore.middleware.SiteMiddleware',
     )
 
+
 # Django 1.10 started to use "MIDDLEWARE" instead of "MIDDLEWARE_CLASSES".
 if V(django.get_version()) < V('1.10'):
     MIDDLEWARE_CLASSES = get_middleware_settings()