Fails to run on Windows when using --production flag

[plampila]

Running on Windows fails when using the --production flag because spawning an npm process fails.

This is because spawn does not use the PATHEXT env var on Windows and does not find the npm command that is actually called npm.cmd. See: nodejs/node-v0.x-archive#2318

Not sure what is the best way to deal with this issue. There is a cross-spawn package. Using shell option for spawn seems to be an option etc.