fix typo in comments.
fix a bug in qhttpserverconnection.

if a socket drops by any mean before http request emits end() signal (network/system failure or
programatically), then the request and response instances will be
deleted.
fix a bug in qhttpclient.

if a socket drops by any mean before http response emits end() signal,
then the request and response instances will be deleted.
add unix socket support to QHttpServer.

* change type of QHttpServer from QTcpServer to QObject.
* add TBackend type to qhttpfwd.hpp.
* change listen() function of QHttpServer.
* change QHttpServer / QHttpServerPrivate to support both tcp and local
 servers.
add QLocalSocket to qhttpconnecion classes.
add QLocalSocket to qhttpserverrequest classes.
add QLocalSocket to qhttpserverresponse.
remove QHTTP_MESSAGES_LOG from server connection.
add Local socket support to qhttp client.
add local socket support to client request.
add local socket support to client response.
modify example/benchmark to support new API.
add QCommandLineParser to example/helloworld + local socket support.
fix a bug in server connection (messageComplete()).

* when an http socket drops, the messageComplete and request->end()
signal will be emitted.

* also request/response instances will be deleted by connection dtor().
add Local socket support to qhttp's client classes.

* also fix a bug when socket drops before messageComplte().

* handler are set before any connection made on QHttpClient::request().

* request/ response pairs are being deleted by their parent.
add local socket support to example/helloworld.
add local socket support to example/benchmark.
add local socket support to README.md
example/helloworld/README.md: add local socket.
example/benchmark/README.md add local socket.