* A bit of refactoring.
* Cleanup mode - remove old package versions and keep only latest one on the remote.
* Metadata regeneration mode. Allows to regenerate metadata without package uploading.
* No script failure when package errored. Just show message and continue.
* Do not leave repository in inconsistent state when terminating uploader with ctrl-c.
* Prevent processing of the duplicated package names in arguments. Argument list will be also sorted.
* Compact informational messages.
It seems that metadata generation take about 40 seconds.
If we submit a new version of package with deleting previous one, users
will observe 404 errors until new metadata will be published.