add example/nodejs : server implementation of example/benchmark.
Url for UNIX (local) sockets : file:///socket_full_path

remove weird socket:// prefix!
QHttpServer now use single listen method for tcp or unix sockets.

also the unix socket will be removed at dtor.
add node.js example in README.md and new qhttp sample.
incomming message can collects the HTTP body now.

server::QHttpRequest and client::QHttpResponse classes have:
* collectData(int)
* collectedData()
methods.
example/nodejs uses collectData() for incoming requests.
node.js example catches JSON.parse exception.
add QHttpConnection::create().
better multithreading in example/benchmark server.
use Qt5 JSON as gason++ in example/nodejs/main.cpp
update README.md files about example/nodejs