webapp secret keys should be regenerated during installation

[Alon Swartz]

Some TurnKey appliances (joomla, mediawiki, django, rails) are vulnerable to a cryptographic weakness due to the usage of a non-secret key.

The secret keys are mainly used in generating/verifying cookie session data.

[Alon Swartz (alonswartz)]

All appliances in the 2009.02 release include this fix.

It is recommended to regenerate the secret key on existing installations of appliances released prior to 2009.02

Joomla
    variable: $secret
    path: /etc/joomla15/configuration.php

Mediawiki
    variable: $wgSecretKey
    path: /etc/mediawiki/LocalSettings.php

Django
    variable: SECRET_KEY
    path: /var/www/django-sites/apps/settings.py

Rails
    variable: :secret
    path: /var/www/railsapp/config/environment.rb