Add Node 8 to Travis and AppVeyor

Author: lencioni

.travis.yml

@@ -1,6 +1,7 @@
 sudo: false
 language: node_js
 node_js:
+  - '8'
   - '7'
   - '6'
   - '5'

appveyor.yml

@@ -4,6 +4,7 @@ environment:
     - nodejs_version: '5'
     - nodejs_version: '6'
     - nodejs_version: '7'
+    - nodejs_version: '8'
 install:
   - ps: Install-Product node $env:nodejs_version
   - set CI=true