Refactor Overlay, HTTP::Server for universal port

These refactorings are required to support the universal port.
Reviewers: @miguelportilla, @scottschurr

Ignore the top 3 (eefc5d9..0ebc9ee) they are from another pull request.
Not at all.  "If it ain't broke, don't fix it".  If we eventually have problems in shutdown, we know where to go.