Change version number from 1.0.0 to 0.1.0

The first official release is unlikely to be a stable product.

E.g. we might choose to change config key and attribute names, so we don't want to tie ourselves to strong support for backwards compatibility until we're definitely ready.

Therefore decreasing (!) the version number seems like the best bet. It will impact all existing users, but better to do it now before we get this built onto sonatype; only people's local .m2 repos will be affected.

---

Please do not merge this until it has been discussed! Opinions extremely welcome!