nw-builder: [BUG] "devDependencies" modules NOT IGNORED when zipping App

Steps to reproduce the bug:

1. put “devDependencies” inside your package.json with all your desired dependences (including nw-builder itself)
2. Run npm install
3. Run nwbuild --platforms win64 .\your_app\path

In the log you can see how \node_modules\nw-builder\... and other modules that are only for a development environment are zipped, causing the final exe to be inflated with all those inservible modules.