Remove node.js 4 in travis config

wong2 · wong2 · commit 6af613959ced · 2018-06-08T16:40:49.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,5 @@
 language: node_js
 node_js:
-- '4'
 - '6'
 - '8'
 before_script:
