Update Travis setup

Author: pmuens

.travis.yml

@@ -2,10 +2,11 @@ language: node_js
 
 matrix:
   include:
-    - node_js: '4.4'
-    - node_js: '5.11'
-    - node_js: '6.2'
-    - node_js: '6.2'
+    - node_js: '4'
+    - node_js: '6'
+    - node_js: '8'
+    - node_js: '10'
+    - node_js: '10'
       env:
         - DISABLE_TESTS=true
         - LINTING=true