adding package.json

Hi,

I wrote a small package.json to be able to add FlowType.JS as a npm dependency.
Now you can : 

    npm install --save kane-thornwyrd/FlowType.JS

Or just set your dependencies object as followed :

    dependencies": {
      "grunt": "^0.4.5",
      "grunt-contrib-jshint": "^0.10.0",
      "grunt-contrib-watch": "^0.6.1",
      "underscore": "^1.6.0",
      "FlowType.JS": "kane-thornwyrd/FlowType.JS"
     },

If you agree to merge this pull request you'll find handy to replace `kane-thornwyrd/FlowType.JS` by `simplefocus/FlowType.JS`.

Eventually you may do some tweak and a `npm publish`.