Update Restbucks example: Conditional GET, PUT.

Added a response method to support resource not
modified.
Added a ETAG_UTILS class to calcule md5_digest.
Added ext libs eel and eapml.

examples/restbucks/src/domain/order.e

@@ -86,6 +86,9 @@ feature -- Etag
 			Result := hash_code.out + revision.out
 		end
 
+
+feature -- Output
+
 feature -- Report
 
 	hash_code: INTEGER_32