Make privateer available via apt, yum, brew, etc

[eddie-knight]

The goal here is to increase the ease of use for CLI and pipeline contexts.

Homebrew

I already spent some time working on releasing to Homebrew, which is evident in the goreleaser process. That work is incomplete, and needs a closer eye to close the gap. The tap repository already exists, and there is a tap file generated in the repo (privateer.rb) but neither are complete or ready to use.

Apt/Yum

I'm thinking that we'll need to make it easy for any CI context to quickly install privateer without building from source.
ref: https://wiki.ubuntu.com/Upstream

Other notes

Right now we've got GoReleaser set up to build the packages and zip the binary w/ the license & readme for each. Is this sufficient for the long term? Do we need to bother with other install processes? If we do something else, it would help to have a more experienced perspective on how to do this properly.

Right now I'm putting this on the backburner because we've got other higher priority features that need work. If anyone reading this has suggestions or the ability to tackle the work, please drop a comment around how you might be able to contribute.