http,net,tls: return this from setTimeout methods

Modifies the setTimeout methods for the following prototypes:

- http.ClientRequest
- http.IncomingMessage
- http.OutgoingMessage
- http.Server
- https.Server
- net.Socket
- tls.TLSSocket

Previously, the above functions returned undefined. They now return
`this`. This is useful for chaining function calls.

PR-URL: https://github.com/nodejs/io.js/pull/1699


Reviewed-By: Roman Reiss <me@silverwind.io>