Update supported Node.js versions

 - Drop everything older than 6.x
 - Add 8.x and 10.x to CI config

Author: bajtos

.travis.yml

@@ -1,7 +1,5 @@
 language: node_js
 node_js:
+  - "10"
+  - "8"
   - "6"
-  - "5"
-  - "4"
-  - "0.12"
-  - "0.10"

appveyor.yml

@@ -1,10 +1,8 @@
 environment:
   matrix:
+    - nodejs_version: '10'
+    - nodejs_version: '8'
     - nodejs_version: '6'
-    - nodejs_version: '5'
-    - nodejs_version: '4'
-    - nodejs_version: '0.12'
-    - nodejs_version: '0.10'
 install:
   - ps: Install-Product node $env:nodejs_version
   - set CI=true

package.json

@@ -40,7 +40,7 @@
     "email": "callback@strongloop.com"
   },
   "engines": {
-    "node": ">=0.6.9"
+    "node": ">=6"
   },
   "preferGlobal": true,
   "devDependencies": {