Automatic cleanup of production-useless files

[mlocati]

Right now, to strip out tests, docs and other useless files from packages installed via composer, we need to manually (and carefully) set the finder key of box.json.

There has been a discussion about the ways about how this process could be automated, delegating to every package maintainer the responsibility to specify which are the files that are superfluous for the production layer.

That discussion resulted in @kamilsk starting a new project to implement this.

It would be fine if Box could support/integrate that project.

[kamilsk]

alpha version is ready, docs here https://github.com/octolab/Cleaner/wiki