Significant rewrite

* Removes a bunch of files that are unused
* Updates significantly to match current Chef workflows
* Renamespaces some attributes to make it a bit easier to wrap your head around
* Other cleanup

See commit messages for more detail. I'll probably do a minor version bump, as I believe this is backwards-compatible, unless particular attribute overrides were set. But I don't think that's worth a full version bump. I'm in the midst of testing this with test-kitchen.
Are instance roles supported?