New debouncing rule type for y2u.be-like bounce trackers

[fmarier]

Zach Edwards discovered a new bounce tracker used in Youtube links: http://y2u.be (note the insecure HTTP scheme)

It works like this: http://y2ube.com/dQw4w9WgXcQ => https://www.youtube.com/watch?v=dQw4w9WgXcQ

These kinds of replacements cannot currently be expressed in our current debouncing list. We'd need a new rule type which extracts a parameter from an existing URL and prepends a hostname to it.

[thezedwards]

Thanks for ya'lls work on this complex issue!