www/p5-Catalyst-Plugin-StatusMessage, because tutorial
recommends to use this module.
The purpose of this plugin is to pass "status message" between screens
through the following mechanisms:
- Stores messages in the "$c->session" so that the application is
free to redirect to the appropriate URL after an action is taken.
- Associates a random 8-digit "token" with each messages, so it's
completely unambiguous what message should be shown in each
window/tab.
- Only requires that the token (not the full message) be included in
the redirect URL.
- Automatically removes the message after the first time it is
displayed. That way, if users hit refresh in their browsers they
only see the messages the first time.