Preliminary experiments

Contains spark jobs, vector tile server, and server side node/mapnik renderer of vector tiles in very preliminary test state.

This release is made because the next steps will involved code refactoring which will discard a lot of the experiments that are not being carried forward. It is foreseen though, that we might need to resurrect some of those ideas at some point in the future, so this release serves only to simplify that process.

This code is not intended to be used by anyone other than the original author and the quality, reusability etc reflect that.