Improve `hyperpack` Flexibility

[johnpatek]

The CLI has the following workflow currently:

1. Specify directory and output path.
2. Archive is built.
3. Archive is overwritten on subsequent calls to hyperpack.

It would be nice to expand this to include more features. In order of priority and complexity:

1. Allow multiple directories to be specified for input.
2. Add a flag or subcommand to list the contents of an archive.
3. Enable compression and encryption of archived data.

[johnpatek]

Closed by #35