Removed any (put|write)_file_content from the WSF_ or WGI_ OUTPUT classes

Now DEFAULT_SERVICE has to be created instead of inherited.
   - This seems to be better for new user, and this avoid potential conflict and difference when inheriting between the various DEFAULT_SERVICE implementation.
   - remember that DEFAULT_SERVICE, is mainly to help the user to build its very first service.
Use READABLE_STRING_8 as argument whenever it is possible.
Added WSF_RESPONSE_MESSAGE, and WSF_RESPONSE.put_response (a_response_message)
Now WSF_RESPONSE inherit from WGI_RESPONSE

library/server/ewsgi/src/helper/wgi_response_stream.e

@@ -115,12 +115,6 @@ feature -- Output operation
 			output.put_substring (s, start_index, end_index)
 		end
 
-	write_file_content (fn: READABLE_STRING_8)
-			-- Send the content of file `fn'
-		do
-			output.put_file_content (fn)
-		end
-
 	flush
 		do
 			output.flush