support dynamic URIs (or metadata)

[drernie]

• scrape the actual publishDir -- capture when Path is created?
• add metadata field to the quilt config

[drernie]

Ah! We can scrape this from the PKGS cache, as all URIs are sent to QuiltPackage.forParsed before QuiltObserver - onFilePublish

That should allow us to get rid of all the params scraping, making it simpler and more robust.