Travis NPM Set to 5.5.1

Author: reconstructions

.travis.yml

@@ -26,7 +26,7 @@ install:
   - bundle install
   - chromedriver-update
   - nvm install stable && nvm alias default stable
-  - npm install npm@latest -g
+  - npm install npm@5.5.1 -g
   - npm install -g yarn
   - npm --version
   - yarn install