Now needs Node 4.8.0 or higher because of yarn

Author: danday74

.travis.yml

@@ -4,6 +4,6 @@ node_js:
   - 8
   - 6
   - 4
-  - 4.0.0
+  - 4.8.0
 after_success:
   - "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"

package.json

@@ -70,6 +70,6 @@
     "sinon-chai": "^3.0.0"
   },
   "engines": {
-    "node": ">= 4.0.0"
+    "node": ">= 4.8.0"
   }
 }