Add package-lock.json

Author: benmccann

.travis.yml

@@ -3,6 +3,7 @@ node_js:
   - "6"
 
 before_install:
+  - "npm i -g npm@5"
   - "export CHROME_BIN=/usr/bin/google-chrome"
   - "export DISPLAY=:99.0"
   - "sh -e /etc/init.d/xvfb start"