copy deps folder

[angerman]

dealing with package local dependencies can be a hassle. The solution here is to force package local dependencies to be in the deps folder. This likely will require some massaging of the package-lock.json; however it's an ok tradeoff to me between auto-detection complexity and offering an escape hatch for local dependencies.

NB: Yes this is an escape hatch hack, but maybe it's a compromise until #18 is solved?