Update CI configs

Author: kristerkari

.travis.yml

@@ -8,16 +8,19 @@ cache:
     - node_modules
 matrix:
   include:
-    - node_js: '9'
+    - node_js: "11"
       script: npm run test -- --runInBand && npm run size
-      env: CI=tests 9
-    - node_js: '9'
+      env: CI=tests 11
+    - node_js: "10"
+      script: npm run test -- --runInBand && npm run size
+      env: CI=tests 10
+    - node_js: "10"
       script: npm test -- --runInBand --coverage && npm run size
       env: CI=coverage
-    - node_js: '8'
+    - node_js: "8"
       script: npm run test -- --runInBand && npm run size
       env: CI=tests 8
-    - node_js: '6'
+    - node_js: "6"
       script: npm run test -- --runInBand && npm run size
       env: CI=tests 6
 before_install:

appveyor.yml

@@ -2,6 +2,9 @@
 
 environment:
   matrix:
+    - nodejs_version: 11
+    - nodejs_version: 10
+    - nodejs_version: 8
     - nodejs_version: 6
 
 version: "{build}"