remove npm steps from travis

pip install runs these steps

.travis.yml

@@ -26,12 +26,11 @@ before_install:
     - nvm install 5.6
     - nvm use 5.6
     - npm upgrade -g npm
-    - npm install && npm run bower
+    - npm install
     - 'if [[ $GROUP == js* ]]; then  npm install -g casperjs@1.1.0-beta5; fi'
     - git clone --quiet --depth 1 https://github.com/minrk/travis-wheels travis-wheels
 
 install:
-    - npm run build
     - pip install -f travis-wheels/wheelhouse file://$PWD#egg=notebook[test]
 
 script: