Cascade up the filesystem hierarchy looking for .kitchen.yml files, and then use that as the root.

Hoping this patch can get in -- if we need to tweak it a little or a lot, I'm happy to make those changes.

The patch allows you to work similar to how bundler works anywhere in the project tree. So, you can be in the `test/` directory, type `bundle exec kitchen converge all -c`, and it just works.

Right now the current solution is to exit with a user error, I think this is a good UI win for a CLI tool.

I might throw some more patches in here surrounding how the `.kitchen` dir gets created (it gets done too early), but please, please open a discussion on how this patch can be made better.

Thanks!