update pkg file

Author: ioslh

package.json

@@ -5,7 +5,7 @@
  "main": "./lib/index.js",
  "scripts": {
  "build": "babel src -d lib",
- "test": "echo \"Error: no test specified\" && exit 1"
+ "prepublish": "npm run build"
  },
  "author": "ohislh@gmail.com",
  "license": "MIT",