provide `rm` command to work with object key versions

[excavador]

By default in versioned S3 bucket Delete operation will insert delete marker.
Sometime you need to clean all object keys version.

Need to provide rm command:

• with ability to choose how to delete - default (delete marker) or all versions
• with option to specify - remove by prefix or exact match (to prevent mistakes, by default rm only for single key, extra flag for prefix)