release 0.6.0

Author: yuanchuan

package.json

@@ -11,7 +11,7 @@
     "watch",
     "watchfile"
   ],
-  "version": "0.5.9",
+  "version": "0.6.0",
   "bugs": {
     "url": "https://github.com/yuanchuan/node-watch/issues"
   },
@@ -22,6 +22,9 @@
   "scripts": {
     "test": "mocha test/test.js --exit --slow 500"
   },
+  "engines": {
+    "node": ">=6"
+  },
   "devDependencies": {
     "fs-extra": "^7.0.1",
     "mocha": "^5.2.0"