Native proxy protocol support

[hueniverse]

Currently, this module: https://github.com/findhit/proxywrap tries to add support for the proxy protocol header, but it's pretty nasty hack. It replaces core node methods in order to hijack traffic to peek at it. Do you think this is something node should provide? If not, can we add some hooks to allow better solutions?

[bnoordhuis]

Related (but not same) discussion: nodejs/node#1490

[hueniverse]

@bnoordhuis I think the scope of proxy support is significantly different from proxy protocol header. Do you have an idea for a better solution than proxywrap? I don't consider hacking core methods to be a valid architecture for anything other than a prototype experiment.