GELF (Graylog2) messages in node.js

Includes chunked messages, so messages can be any size
(couldn't find another node.js lib that does this)

``javascript
var gelfling = require('gelfling')

var client = gelfling()

client.send('Message', function(err) { console.log('Sent') })

client.send({ short_message: 'Message', facility: 'myApp', level: gelfling.INFO })

var complexClient = gelfling('localhost', 12201, {
defaults: {
facility: 'myApp',
level: gelfling.INFO,
short_message: function(msg) { var txt = msg.txt; delete msg.txt; return txt }
myAvg: function(msg) { return msg.myTotal / msg.myCount }
}
})

complexClient.send({ txt: 'Hi', myTotal: 1337, myCount: 23 })
``