Remove machine values

With the move over to controlling all sources with openaddresses/machine, machine variables in the json are no longer necessary and therefore deprecated.

This is a breaking change. Anyone depending on the `cache`, `processed`, `fingerprint`, or `version` attributes should update their code to point to the new data schema at data.openaddresses.io

cc/ @iandees @migurski Could you do a quick review and merge if this sounds good?