Hi James,
The manual httpclient test is rather incomplete. While it does take a "command" and "arguments" (as well as credentials) on the command line, the host/port is hard coded, and as far as I can tell it only sends the command (no arguments). I wrote this very quickly and gave it less importance since I had made the automated tests for the class.
The manual test is meant to serve as an example of how to use the http client class, and it was also written to be tested against a bitcoind server (this was the original usecase). It does seem like if you change line 66 to:
HttpClient client("
http://127.0.0.1:5555");
and run the HttpServer manual test, it should work (without any arguments). I would gladly accept pull requests to fix these if they are unclear, and am working on getting documentation in very soon.
Matt