Enable GZIP compression in the HttpServer and decompression in the HttpClient.

- Adds a handler to the DefaultHttpClient to decompress the incoming payloads if the response header contains a "Content-Encoding: gzip" field.  Also a switch to turn on/off this function.

- Adds a handler to the DefaultHttpServer to compress the outgoing payloads if the request header contains an "Accept-Encoding: gzip" field.  Also a switch to turn on/off this function.
Merge pull request #1 from liuxuc/gzip_support

Enable GZIP compression in the HttpServer and decompression in the HttpC...