virtual_http_servers():
  - listen() method renamed bind(), binds virtual server to upstream http server
  - redefine listen() method to request upstream http server listening if not yet listening
http_servers():
  - overload listen() to listen to preset port and ip address if not yet listening
http_listen():
  - use http_server listen() method to listen if not yet listening
Merge branch 'master' of https://github.com/ConnectedSets/ConnectedSets