Merge changes from Javier

- update on RESTbuck examples
- new example
- fixed bad typo in WSF_REQUEST

Reverted some changes such as
- http_client_response: keep the headers as a list to handle multiple message-value with same message-name

Fixed simple and simple_file example
Improved HTTP_HEADER

Changed libcurl implementation for http client
- now the header from the context really overwrite any of the session headers
- better design which is more strict, and remove any doubt about context's header usage

examples/simple/application.e

@@ -0,0 +1,30 @@
+note
+	description : "simple application root class"
+	date        : "$Date$"
+	revision    : "$Revision$"
+
+class
+	APPLICATION
+
+create
+	make
+
+feature {NONE} -- Initialization
+
+	make
+			-- Run application.
+		local
+			s: DEFAULT_SERVICE
+		do
+			create s.make_and_launch (agent execute)
+		end
+
+	execute (req: WSF_REQUEST; res: WSF_RESPONSE)
+		do
+			-- To send a response we need to setup, the status code and
+			-- the response headers.
+			res.write_header ({HTTP_STATUS_CODE}.ok, <<["Content-Type", "text/plain"], ["Content-Length", "11"]>>)
+			res.write_string ("Hello World")
+		end
+
+end