version.sh: integrate the release tag in output

This is basically reconstructed from 46b218c. Since we now have proper
release tags, we want this again.

Add --tags to the git describe call, because the github release system
creates light-weight tags only, and we're too lazy to create annitated
tags (or is that bad practice?).

Add --long, so that the git commit hash is part of the output even if
the tag matches.