added HTTP headers "pazpar2-version", "pazpar2-server-host", "pazpar2-server-port...

added HTTP headers "pazpar2-version", "pazpar2-server-host", "pazpar2-server-port", "pazpar2-remote-host", and "pazpar2-remote-port" such that the HTTP proxy PHP script can fetch these values and use them for authentification and other pazpar2 specific stuff (this is needed, because the "Remote-Addr" PHP variable  is always set to the paraz2 server IP adress, due to tunneling through pazpar2.
The only thing which needs completion  is actually finding the correct values for these host and port parameters from the server configuration and the TCP/IP connection object. More digging in the source is needed to find these values the right places..