language: python
python:
  - 3.5
  - 3.6
install:
  - pip install .
script:
  - pip install pint
  - nosetests

language: python
python:
  - 3.5
  - 3.6
env:
  - RUN_PEP8=0
  - RUN_PEP8=1
matrix:
  exclude:
    - python: 3.5
      env: RUN_PEP8=1
  allow_failures:
    - env: RUN_PEP8=1
install:
  - pip install .
script:
  - pip install pint
  - nosetests
  - |
    if [[ "${RUN_PEP8}" == "1" ]]; then
      pip install flake8
      flake8
    fi

Add flake8 check to Travis CI configuration.
Add flake8 check to Travis CI configuration.

Add an additional optional flake8 run to the list of Travis CI builds.
This test is allowed to fail without breaking the build.
