superfluous pip install in travis_test.sh

tests/travis_test.sh

@@ -5,7 +5,6 @@ set -x
 curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
 chmod +x ./cc-test-reporter
 ./cc-test-reporter before-build
-pip install nose2 coverage
 
 python setup.py install
 pip install -r stress_tests/requirements.txt