Update hotbuild upgrade action for engymod

Closes #34, but exposes a bug:

It's possible to build supportfactories without having the required HQ,
although they will not be able to build higher tier units.

I've ductaped this now in this buildaction, but that's not really a guarantee.
Merge pull request #65 from FAForever/feature/hotbuild-upgrade-engymod

Update hotbuild upgrade action for engymod