Update node versions to test

Author: compwright

.travis.yml

@@ -1,13 +1,8 @@
 language: node_js
 
 node_js:
-  - 4
-  - 4.0
   - 6
-  - 6.0
-  - 7
-  - 7.0
   - 8
-  - 8.0
+  - 10
 
 sudo: false

package.json

@@ -35,6 +35,6 @@
     "supertest": "^3.3.0"
   },
   "engines": {
-    "node": ">=4.0"
+    "node": ">=6"
   }
 }