Build With Travis CI

I started working on a feature for Spreewald and noticed it isn't being built with [Travis](https://travis-ci.org/). Since I don't really want to install an unsupported version of Ruby to test my feature (\*cough\* 1.8.7 \*cough\*), having Travis do the hard work is much more preferable.

You'll need to enable this, so [check out the docs](http://about.travis-ci.org/docs/user/getting-started/#Step-one%3A-Sign-in). I think I've done the bulk of the hard work here. You may also want to put the [build badge](http://about.travis-ci.org/docs/user/status-images/) into the README afterward.