initial cpack implementation

[Aposhian]

Addresses #894.

This adds a very simple cpack implementation, supporting debian and source (non-distro specific) generators so far.

Adding RPM support is probably trivial, but I just need to test what additional vars need to be set.

@COM8 I figure the package contact should probably be you, but I don't know what contact email to put. I've also seen packages where the debian maintainer is listed here, not necessarily the upstream maintainer. So not exactly sure on that.

[Aposhian]

I'll take a look.

[COM8]

Closing since this one is stale.