net: add pauseOnConnect option to createServer()

Currently, when a server receives a new connection, the underlying socket handle begins reading data immediately. This causes problems when sockets are passed between processes, as data can be read by the first process, and thus never read by the second process. This commit allows sockets that are constructed with a handle to be paused initially.

@trevnorris this is the behavior I referenced on https://github.com/joyent/node/issues/7905#issuecomment-58410500, which we subsequently discussed on IRC. I plan on looking into UDP sockets next.

Closes #7905. Closes #7784.
style nit: if one part of an `if`/`else` uses brackets all of them should. don't worry about fixing it though. i'll take care of it before merging.