fix(travis.yml): pin Node.js version to 6 (#28)

jshcrowthe · web-flow · commit f70c7f2c1c09 · 2017-06-01T10:38:04.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,7 +1,7 @@
 sudo: required
 dist: trusty
 language: node_js
-node_js: stable
+node_js: "6"
 env:
   - CXX=g++-4.8
 cache: yarn
