enhance bower support

If you use something like wiredep, since this project lacks a "main" property in bower.json you will get an error like
![screenshot 2014-04-14 15 42 43](https://cloud.githubusercontent.com/assets/2192970/2700649/0c664a74-c416-11e3-8bea-86e7134ada8c.png)

Adding a proper bower.json fixes this