Use git tags to tag published cargo versions

[msvbg]

It's helpful to be able to see which version of the source code corresponds to which version published on crates.io, so it would be great if the git repo were tagged accordingly. It may also make sense to use the same version number for all crates given that this is a monorepo of sorts.

[idanarye]

It's a monorepo, but the crates get updated individually. If I force them all to use the same version there will be version gaps.