chore: update npm configuration in `dependencies-npm.sh` (#961)
chore: update npm configuration in `dependencies-npm.sh` (#961)

- The Electron npm headers can now be downloaded from
  https://atom.io/download/electron

- We can configure gyp to build from source by using the
  `npm_config_build_from_source` environment variable rather than having
  to pass `--build-from-source`

Signed-off-by: Juan Cruz Viotti <4148f5869aa1bcd7efd85b513a5874967e585032@openmailbox.org>
resin-io/resin-etcher,resin-io/etcher,resin-io/etcher,resin-io/resin-etcher,resin-io/etcher,resin-io/herostratus,resin-io/etcher,resin-io/herostratus,resin-io/etcher