crowbar-prep.sh: add -r option for setting sledgehammer root pw
crowbar-prep.sh: check we have a FQDN
crowbar-prep.sh: ensure commands succeeded
crowbar-prep.sh: rename misleading sc2_repo variable
crowbar-prep.sh: minor tweaks to versioning

Add new --product-version switch.
Merge pull request #26 from aspiers/master

Looks good to me.