Run isort as part of 'make lint'

.drone.yml

@@ -8,7 +8,7 @@ pipeline:
     image: python:3.5
     commands:
       - XDG_CACHE_HOME=/drone/pip-cache pip install wheel
-      - XDG_CACHE_HOME=/drone/pip-cache pip install isort -e .[testing,docs]
+      - XDG_CACHE_HOME=/drone/pip-cache pip install -e .[testing,docs]
       - isort --check-only --diff --recursive wagtail
   js:
     image: node:4.2.4

Makefile

@@ -17,6 +17,7 @@ develop: clean-pyc
 
 lint:
 	flake8 wagtail
+	isort --check-only --diff --recursive wagtail
 
 test:
 	python runtests.py

setup.py

@@ -46,6 +46,7 @@ testing_extras = [
     # For coverage and PEP8 linting
     'coverage>=3.7.0',
     'flake8>=2.2.0',
+    'isort>=4.2.0',
 ]
 
 # Documentation dependencies