Add Version command not respecting semver

[aschmahmann]

When doing ./add-version <repo> <version> for a patch release of the repo that is semver-wise later than the new version the current file points to the patch release rather than staying with the latest version.

Additionally, although less problematically, when the patch release is added to the versions file it is added at the end of the file rather than being added at the semver-wise correct spot.