Tests and readme

This adds tests and extends the readme.

If you are going to have the badges I propose for the README, you will need to add the project to https://travis-ci.org/ and https://gemnasium.com/ but I think it's well worth it to prove it has at least some tests, and as the badge will show that it has no dependencies (always a plus) if you merge #1

It's important that this gets used by projects other than jade, so that more people are invested in keeping it up to date.