support the socks5 proxy.

[sundq]

implement the sock5 proxy.

[mattcg]

Hi - I'm the author of the libraries included in the commit. While I'm in favour of adding socks support to request, I don't think this is the best way to do it. The library files should not be added to lib/ - they should instead be added to package.json as dependencies.

If you like, close this pull request and I'll make another one with a clean implementation.

[mikeal]

actually, the best way to do this is to publish this sock5-agent as its own module and depend on that. I'd gladly accept that patch.

[mattcg]

Thanks for jumping in!

The agents (there's one for HTTP and another for HTTPS) have already been published as their only modules... sorry, that's what I was trying to say :)

I'll make the pull request.

[mikeal]

no longer merges cleanly :(