Added parameter to accept encoding

Hi,

I've implemented a new feature in your ProxyServlet. It was a requirement in my system to avoid the compression (remove ACCEPT ENCODING from the header). So I've changed the ProxyServlet to receive one more parameter and check if the value of gzip is false. In case of false, proxy will disables gzip compression (doesn't set ACCEPT-ENCODING header). Default value is true (keeps ACCEPT-ENCODING header "as is").
Sorry about change your code, it's just a way to improve a good class that you already created.
Please, let me know if you have anything to say about it.

Thanks