One Dot Oh™ and Semantic Versioning

It appears this project has reached significant enough adoption that we should be seriously contemplating compatibility issues when making changes.  Moving forward, I'm going to use [semantic versioning](http://semver.org) to give provide clarity around backwards compatibility.

Next week, I'm going to tag the `v1.0.0` release.  If anyone has any important API-breaking changes, now is the time to open a PR.  After that, I'm going to try to keep the API stable unless there's a really good reason to break something.  Between now and then, I'm going to make a cleanup pass and make sure everything is consistent.