chore(travis): test in node maintenance/LTS/stable versions

Author: gr2m

.travis.yml

@@ -1,12 +1,8 @@
 language: node_js
 node_js:
-  - "node" # latest stable Node.js release
-  - "7"
+  - "8"
   - "6"
-  - "5"
   - "4"
-  - "0.12"
-  - "0.10"
 notifications:
   email: false
 sudo: false