~~ TIME SERVER ~~

Write a TCP time server!

Your server should listen to TCP connections on port 8000. For each
connection you must write the current date & time in the format:

YYYY-MM-DD hh:mm

followed by a newline character. Month, day, hour and minute must be
zero-filled to 2 integers. For example:

2013-07-06 07:42

----------------------------------------------------------------------
HINTS:

For this exercise we'll be creating a raw TCP server. There's no HTTP
involved here so we need to use the `net` module from Node core which
has all the basic networking functions.

The `net` module has a method named `net.createServer()` that takes a
callback function. Unlike most callbacks in Node, the callback used by
`createServer()` is called more than once. Every connection received
by your server triggers another call to the callback. The callback
function has the signature:

function (socket) { ... }

`net.createServer()` also returns an instance of your `server`. You
must call `server.listen(portNumber)` to start listening on a
particular port.

A typical Node TCP server looks like this:

var net = require('net')
var server = net.createServer(function (socket) {
// socket handling logic
})
server.listen(8000)

The `socket` object contains a lot of meta-data regarding the
connection, but it is also a Node duplex Stream, in that it can be
both read from, and written to. For this exercise we only need to
write data and then close the socket.

Use `socket.write(data)` to write data to the socket and
`socket.end()` to close the socket. Alternatively, the `.end()` method
also takes a data object so you can simplify to just:
`socket.end(data)`.

Documentation on the `net` module can be found by pointing your
browser here:
C:\Users\dzhang\AppData\Roaming\npm\node_modules\learnyounode\node_apidoc\net.html

To create the date, you'll need to create a custom format from a
`new Date()` object. The methods that will be useful are:

date.getFullYear()
date.getMonth() (starts at 0)
date.getDate() (returns the day of month)
date.getHours()
date.getMinutes()

Or, if you want to be adventurous, use the `moment` package from npm.
Details of this excellent time/date handling library can be found
here: http://momentjs.com/docs/

----------------------------------------------------------------------

timeServer.js

var net = require('net');

function zero(num){

    num = (num > 10 ? "" : "0" )+ num;

    return num;

}

function now(){

    var d = new Date();

    return d.getFullYear()+"-"+zero(d.getMonth()+1) +"-"+ zero(d.getDate())+" "+zero(d.getHours())+":"+zero(d.getMinutes());

}

var server = net.createServer(function(socket) { //'connection' listener

    socket.end(now() + "\n");

});

server.listen(8000);