Replace nose with unittest in Travis CI script

And directly use coverage.py

Author: Harmon758

.travis.yml

@@ -35,7 +35,8 @@ script:
   # Make sure we limit open handles to see if we are leaking them
   - ulimit -n 128
   - ulimit -n
-  - nosetests -v --with-coverage
+  - coverage run --omit="git/test/*" -m unittest --buffer
+  - coverage report
   - if [ "$TRAVIS_PYTHON_VERSION" == '3.5' ]; then cd doc && make html; fi
   - if [ "$TRAVIS_PYTHON_VERSION" == '3.6' ]; then flake8 --ignore=W293,E265,E266,W503,W504,E731; fi
 after_success: