Create package.json

Just to allow people to use npm install with something like that in their own package.json: 

    "devDependencies": {
      "grunt": "~0.4.5",
      "grunt-contrib-yuidoc": "^0.5.2",
      "yuidoc-themes": "Krxtopher/yuidoc-themes"
    }

It's more convenience than real killer feature.