boilerplate: Add Node.js 9 support

RobLoach · web-flow · commit 16b3a6131ced · 2017-11-28T00:21:00.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -6,6 +6,7 @@ node_js:
   - "6"
   - "7"
   - "8"
+  - "9"
 
 after_success:
   - npm run coverage
