Hook restana directly into http.createServer()

[schamberg97]

This PR allows restana to be directly hooked into http native server like this:

'use strict'

const http = require('http')
const service = require('restana')()

service.get('/hi', (req, res) => {
  res.send({
    msg: 'Hello World!'
  })
})

http.createServer(service).listen(3000, '0.0.0.0', function () {
  console.log('running')
})

[jkyberneees]

Hi @schamberg97, this is GREAT. Could you also add the test cases for this feature? Update the docs? Let me know otherwise, I can do it as well with pleasure.

Regards.

[schamberg97]

hold on, gimme half an hour

[schamberg97]

Done, hopefully these new commits will pass the checks!

[schamberg97]

@jkyberneees it appears something has gone terribly wrong with Travis CI integration, as it reports the build is done, while GitHub still has outdated information. Perhaps re-run is needed.