Need an installer for scratch on windows -- 2

We need a couple of windows scripts to be done. We need to be able to run development versions of the following project on windows. The users who are running these are not developers, so the script needs to set it up for them

https://github.com/LLK/scratch-gui
with its dependency
https://github.com/LLK/scratch-vm

In short:

Installer:
- Make sure NPM and Git are installed
- Install both of the above repos
- Do an npm link in the scratch-vm repo
- Do an npm link scratch-vm in the scratch-gui repo

Runner:
- start: do an npm start in the scratch-gui repo
- stop: stop the relevant npm process

Updater:
- should update the scratch-gui and scratch-vm repos from repos/branches we specify