'net' module: tests and fixes

So far this updates #308 with a very basic test suite, and fixes IPv4 and/or IPv6 address detection.
You're right, looks like its not per socket. Also note that a `aucInactivity=0` is infinity timeout and a [Node setTimeout of 0](http://nodejs.org/api/net.html#net_socket_settimeout_timeout_callback) disables idle timeouts since by default timeouts are infinity. Maybe use `setTimeout(null)` to be `aucInactivity=0`?

I like your suggestion. Alternative methods might also be: 

1. Set it to infinity globally and then aggressively poll for the early (10-20s timeouts) and close those out unless `.setTimeout` is called differently.
2. Set it to infinity globally and start terminating sockets if we get 4 sockets open and none have received data in a while. So everytime we receive/send data on a socket log the uptime with the socket and on the 5th open socket check the last 4 and close out the least used...? That seems annoying to track though.
3. Set it to infinity globally and throw some errors once we get past available sockets.