Update package.json

Make things look nice on https://www.npmjs.org/package/ember-sync and on http://addons.builtwithember.io

Currently looks like this:
![screen shot 2014-09-09 at 11 24 41 am](https://cloud.githubusercontent.com/assets/61048/4204200/706df3a8-3835-11e4-8103-0f91e46bf1ee.png)