Update asconfig command

- add an 'info' command to show metadata.
- Replace InputSupplier with ByteSource and ByteSink
- remove Generator and ZipGenerator, have ZipPackager use ByteSource
- allow init to omit the release or snapshot repo or both. Make release and snapshot smart enough
  to skip deployment if no remote repository is configured (required for local-only testing)
- Output groupId in various places to make the output align closer with GAV coordinates
- number of small fixes, mostly NPE edge conditions with no release and/or snapshot repository