drop Node 4,5 until LTS

.travis.yml

@@ -1,18 +1,18 @@
 sudo: false
 language: node_js
 node_js:
-  - "4"
-  - "5"
   - "6"
   - "7"
   - "8"
+  - "9"
+  - "10"
 matrix:
   include:
-    - node_js: "7"
+    - node_js: "6"
       env: TEST_SUITE=standard
-    - node_js: "7"
+    - node_js: "6"
       env: TEST_SUITE=coverage
 env:
-  - TEST_SUITE=integration
   - TEST_SUITE=unit
+  - TEST_SUITE=integration
 script: npm run-script $TEST_SUITE