Lightweight install client in nodejs

[springmeyer]

@kkaefer has proposed a lightweight bash client in https://github.com/mapbox/mason/tree/client which has the promise to be the standard way we install packages via the command line soon. I'm creating this ticket to log the need for another client that is portable to windows.

The problem is:

• node-mapnik currently depends on header-only packages via npm (protozero and mapnik-vector-tile)
• It was decided at Docs on publishing of header-only C++ libs (include in node c++ modules) cpp#20, that we want to move away from publishing header only libs to npm, and only do it to mason
• this means that node-mapnik needs a mason client that runs on windows

[springmeyer]

I think this client should be written in nodejs. The design would be:

• separate nodejs module (does not need to be stored in mason repo)
• published to npm
• a node js c++ addon could depend on it as a devDep
• it would be able to download a mason package and put it inside mason_packages in the same format as the bash mason client and the cmake mason client

[springmeyer]

Closing, this: work is now underway on a node.js client at https://github.com/mapbox/mason-js