v0.0.6

Changelog

This is basically a complete rewrite, changing the approach from making use of
Heroku's build infrastructure via a compiler app, to reimplementing a version
of Heroku's Slug Compiler.

This means that there's more control over the build process, and it's more fun :)

In theory people could run this on much beefier boxes, with better caching of
whatever they need to build their apps.