devel/npm-minidump: Add the port to the tree
This privides stackwalker/minidump feature installed by npm for node modules.
It's needed as separate ports as an important component to build electron.io

Reviewed by: mat (mentor)
Approved by: mat (mentor)
Sponsored by: Essen Hackathon 2017
Differential Revision: https://reviews.freebsd.org/D11630