Add lint step to travis

This is to ensure that pull requests fail when they don't obey pep8
enough.

.travis.yml

   - 2.7
 install:
 script:
-  - pip install -r requirements.txt
-  - ./setup.py develop
-  - ./runtests.py
+  - make travis

Makefile

 # These targets are not files
-.PHONY: contribute ci test i18n
+.PHONY: contribute ci test i18n lint travis
 
 install:
 	python setup.py develop
 	sites/sandbox/manage.py loaddata countries.json sites/_fixtures/pages.json sites/_fixtures/auth.json
 	sites/sandbox/manage.py rebuild_index --noinput
 
-ci:
+test: 
+	./runtests.py tests/
+
+ci: install lint
 	# Run continous tests and generate lint reports
-	python setup.py develop
-	pip install -r requirements.txt
 	./runtests.py --with-coverage --with-xunit
 	coverage xml
-	flake8 --ignore=W292,E202 oscar | perl -ple "s/: /: [E] /" | grep -v migrations > violations.txt
 
-test:
-	./runtests.py
+lint:
+	./lint.sh
+
+travis: install test lint
 
 i18n:
 	# Create the .po files used for i18n 

lint.sh

+#/usr/bin/env bash
+
+ERRORFILE="violations.txt"
+THRESHOLD=1050
+IGNORE="W292,E202"
+
+flake8 --ignore=$IGNORE oscar | perl -ple "s/: /: [E] /" | grep -v migrations > $ERRORFILE
+
+# Check that the number of violations is acceptable
+NUMERRORS=`cat $ERRORFILE | wc -l`
+if [ $NUMERRORS -gt $THRESHOLD ]
+then
+	echo 
+	echo "Too many flake8 errors - maximum allowed is $THRESHOLD, found $NUMERRORS"
+	echo 
+	echo "To fix, run 'make lint' and examine $ERRORFILE"
+	exit 1
+fi