Run flake8 using Travis CI

.travis.yml

@@ -34,11 +34,13 @@ before_install:
   - if [[ $TRAVIS_OS_NAME == "osx" ]]; then source venv/bin/activate; fi
   - pip install -U pip
   - pip install -U coveralls
+  - pip install -U flake8
 install:
   - pip install -Ur requirements.txt
   - python setup.py develop
   - rm -rf build
 script:
+  - flake8
   - export COVERAGE_PYTHON_VERSION=python-${TRAVIS_PYTHON_VERSION:0:1}
   - export RUN_TESTS="coverage run --source=thefuck,tests -m py.test -v --capture=sys tests"
   - if [[ $TRAVIS_PYTHON_VERSION == 3.5 && $TRAVIS_OS_NAME != "osx" ]]; then $RUN_TESTS --enable-functional; fi