doc: Clean up net.Socket

doc: Clean up net.Socket

net.Socket::connect(options[, connectListener]) was missing, with the
relevant details found on the net.connect function. I moved the
appropriate documentation over and then rewrote the documentation for
the function to say that it just creates a socket and calls the connect
method on it. I also changed the other net.Socket::connect variants to
say they are like the options version but called with a specific
options object.

net.connect and other functions were called methods even though they
don't use the `this` binding, so I changed method to function where
appropriate.

Finally, I added a missing period to the end of the module summary.
It's not really related to the rest of the changes, but benjamingr
noticed it.

PR-URL: https://github.com/iojs/io.js/pull/951
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Christian Tellnes <christian@tellnes.no>