Added Nowin hosting back and made it the default

Hosting on Kestrel is still available via "k web-kestrel"
Fixed port in README
Merge pull request #8 from akoeplinger/nowin

 Added Nowin hosting back and made it the default
Merge pull request #7 from desdesdes/master

Cleanup after remove of Firefly dependency
Added Websocket demo

- Updated NowinServerFactory to support vnext websockets
- Addd WebSocketMiddleware for kestrel