- label capitalization and related cleanups

- Add release stage and lifecycle url

- Reduce busybox image size by removing Index.db
Index.db is being created on demand by rpm(1) (as long as it is run as root)
so we don't strictly have to ship it. currently the Index.db has a lot of
empty space within which we could optimize away.
until then removing the file saves 10% of the total compressed size.
- switch versioning to rolling Tumbleweed schema

- Add org.opencontainers.image.source label set to %SOURCEURL%

- Bump copyright year