No versions found in startbootstrap-sb-admin-2.git

No versions found in https://github.com/IronSummitMedia/startbootstrap-sb-admin-2.git

The problem manifests itself because IronSummitMedia changed it's name to BlackrockDigital and you should go and install a different package from:

https://github.com/BlackrockDigital/startbootstrap-sb-admin-2