WIP: Drop --tags from git describe

[agx]

With #96 applied we can drop --tags from describe making sure git describe only picks up annotated tags. This allows e.g. users hacking on uuu to use lightweight tags in their working copy without tripping up uuu_get_version().

This should be appplied after #96 and after at least one annotated tag was created. I will rebase this commit if/once #96 is applied.