Update to the latest Node.js LTS version.

westy92 · FagnerMartinsBrack · commit 31b3366b0384 · 2017-08-19T11:01:18.000+10:00
Closes js-cookiegh-328.
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - '5.1.1'
+  - '6'
 # Only use grunt-ci for commits pushed to this repo. Fall back to regular test
 # for pull requests (as secure variables won't be exposed there).
 script:
