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.
"new" has a way of going stale quickly.  Perhaps something like, "... peer connections use an HTTP request handshake interface as an alternative to the legacy TMHello..."