[Tests] remove node 5/7/9, add node 11

Author: ljharb

.travis.yml

@@ -1,12 +1,10 @@
 sudo: false
 language: node_js
 node_js:
+  - '11'
   - '10'
-  - '9'
   - '8'
-  - '7'
   - '6'
-  - '5'
   - '4'
 before_install:
   - 'nvm install-latest-npm'
@@ -30,11 +28,7 @@ matrix:
     - node_js: 'lts/*'
       env: PRETEST=true
   exclude:
-    - node_js: '5'
-      env: ESLINT=5
     - node_js: '4'
       env: ESLINT=5
   allow_failures:
-    - node_js: '9'
-    - node_js: '7'
-    - node_js: '5'
+    - node_js: '11'