Set travis ci node version

Author: robbinjohansson

.editorconfig

@@ -11,7 +11,7 @@ end_of_line = lf
 insert_final_newline = true
 trim_trailing_whitespace = true
 
-[{package.json,*.scss,*.css}]
+[{package.json,*.yml,*.yaml,*.scss,*.css}]
 indent_size = 2
 
 [*.md]

.travis.yml

@@ -1,6 +1,8 @@
 language: node_js
 node_js:
-    - 'stable'
+  - '9'
+  - '8'
+  - '7'
 script:
-    - yarn lint
-    - yarn test
+  - yarn lint
+  - yarn test