feat(travis): remove node 6 and 7

Walker Leite · Walker Leite · commit 90cc789bf728 · 2018-02-20T18:08:24.000-03:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,7 +1,6 @@
 language: node_js
 node_js:
-  - "6"
-  - "7"
+  - "8"
   - "node"
 addons:
   chrome: stable
