Fix .travis.yml to use flake8, not pyflakes
Fix .travis.yml to use flake8, not pyflakes

nickjj/build-a-saas-app-with-flask,z123/build-a-saas-app-with-flask,z123/build-a-saas-app-with-flask,nickjj/build-a-saas-app-with-flask,nickjj/build-a-saas-app-with-flask,nickjj/build-a-saas-app-with-flask,z123/build-a-saas-app-with-flask