The reason plugins are not in the main git is that each of them has its own repo. Which begs the question - why are they copied from a release zip and not cloned from repos?
There are a few more funnies there: .gitignore does not ignore the binary files added by these scripts, if there is a new node-webkit and then LightTable release and you re-run the script, your local old node-webkit copy will overwrite the new copy you just downloaded :)
Someone needs some solid packaging help. Oh and node-webkit people need a LOT of very good packaging help. Their build process is so convoluted, it might actually spawn an extra-dimensional entity.