refactored the HTTPParser

It, as of now, properly handles everything related to parsing.
It should be fed with data via the insertion operator and the parsing starts
automatically, if there is an error doring parsing the
parseError(const QString &reason) signal is emitted or if the parse is succesful
parsed() is emitted. Please note that you can send data as it's received from
the network to the parser, since if it cannot parse what it already has, it will
wait for more data until it can parse it.
URL-decoding the POST data and parsing after the full input arrived

I parse only after the whole input arrived since I want to keep the code simple,
parsing only fragments would complicate it, I'm aware that this may cost me
speed, but it's not a problem since it's a toy daemon.
HTTPConnection uses the new HTTPParser to parse the request and to send a response after parsing
cleanup
new .gitignore