Update package.json

Make things look nice on https://www.npmjs.org/package/ember-split-view and on http://addons.builtwithember.io

Currently looks like this:
![screen shot 2014-09-09 at 11 23 06 am](https://cloud.githubusercontent.com/assets/61048/4204166/37af8680-3835-11e4-862d-c6060a9a0bec.png)