Merge pull request #119 from Emantor/fix/travis_setuptools

travis.yml: work around pypa/setuptools#1086

.travis.yml

@@ -7,6 +7,7 @@ before_install:
   - sudo apt-get -qq update
   - sudo apt-get install -y libow-dev
 install:
+  - pip install --upgrade setuptools
   - pip install --upgrade pytest pytest-mock pytest-cov coveralls codecov
   - pip install -r dev-requirements.txt
   - pip install -e .