Continuous integration!

Hi,

I don't know if you've already tried Travis or some other continuous integration, but if you want to try it with domino.js, just merge this.

If you do so, don't forget to:
* Sign up on travis-ci.org with your Github account
* Switch on this repo in your accounts settings
* Change the first line of README.md to `[![Build Status](https://travis-ci.org/jacomyal/domino.js.png)](https://travis-ci.org/jacomyal/domino.js)`
* Push something on your repo to see the build pass