bump package deps

Author: Dave Conway-Jones

.travis.yml

@@ -1,10 +1,12 @@
 sudo: false
 language: node_js
 node_js:
-  - "8"
   - "6"
+  - "8"
+  - "10"
 before_script:
   # Remove the './node_modules/.bin:' entry, see https://github.com/travis-ci/travis-ci/issues/8813
+  - npm i -g npm
   - export PATH=`echo ${PATH} | sed -re 's,(^|:)(./)?node_modules/.bin($|:),\1,'`
   - npm install -g istanbul grunt-cli coveralls
   - npm install node-red