Separate configurable variables to config.js

There is some hard coding with irc channel name, bot nick name ...etc .
I separate those var into an isolated file, config.js, and there is an sample file provided.
To include the config.js, just use ```var config = require('./config.js')```
The `config` object has the following structure current.
```javascript
{
  server: {
    port: 80,
  },
  irc: {
    server: 'chat.irc.freenode.net',
    channel: '#sitcon',
    bot_nick: 'SITCON_BOT',
    bot_pwd: 'sitcon_bot_pwd',
}
```
Maybe this struct should be provided in documentation.

I think this seat system can also be used in other conference, so i try to make it configurable.