Add RestSslClient; add User-Agent header.

example/http_ssl_client/main.cc

@@ -7,10 +7,14 @@ void Test() {
   webcc::HttpRequest request;
   request.set_method(webcc::kHttpGet);
   request.set_url("/LICENSE_1_0.txt");
-  request.SetHost("www.boost.org", "443");
-  request.UpdateStartLine();
+
+  // Leave port to default value.
+  request.set_host("www.boost.org");
+
+  request.Make();
 
   webcc::HttpSslClient client;
+
   if (client.Request(request)) {
     std::cout << client.response()->content() << std::endl;
   } else {