const correctness
HTTPThread::processRequestData() is now const-correct and returns a QByteArray

* it determines if it has to serve a static file by checking the presence of the
* query string and if so then it fetches the contents of the file or directory.
* In case the file or directory is not readable or is inexistent it should return
* a QByteArray containing the appropriate HTTP status code.
check to ensure the docroot is readable
proper check for protocol and proper constants
using the constant responseStatulLine to generate the reponses consistently
implemented HTTPThread::serveStaticDir()