Update the restbuck_client, still work in progress.

Update restbuck_server, remove unused class in inherit.
Update libcurl_http_client_request, to parse context headers before the
execution.
Update wgi_input_stream, commented precondition.

library/client/http_client/src/spec/libcurl/libcurl_http_client_request.e

@@ -167,7 +167,15 @@ feature -- Execution
 					p := curl.slist_append (p, curs.key + ": " + curs.item)
 				end
 			end
-
+			if ctx /= Void then
+				if attached ctx.headers as l_headers_2 then
+					across
+						l_headers_2 as curs_2
+					loop
+						p := curl.slist_append (p, curs_2.key + ": " + curs_2.item)
+					end
+				end
+			end
 			p := curl.slist_append (p, "Expect:")
 			curl_easy.setopt_slist (curl_handle, {CURL_OPT_CONSTANTS}.curlopt_httpheader, p)