Adding automatic OS-level packaging

[jhermann]

Once you settled the zip-safe challenges etc., it'd be nice if exxo could add a packaging envelope via an option or configuration value.

Rationale:

• Solves the "external shared object" dependency problem
• Since the package contents is so simple, automated packaging is too, and saves writing boring packaging tool config files (metadata is readily available from setup.py)

If you come around to this, I'd be willing to help with Debian (DEB/APT).