Previously, a NotAllowedException would be thrown if an invalid session
was encountered. However, these exceptions were not caught, and hence
would yield a fatal uncaught exception error.
At this point in Kabuki, the ErrorHandler class has not been registered yet
for error handling purposes. This error is therefore not visible if the PHP
ini directive 'display_errors' is set to 'Off'. As this is the default
production value, the script would fail with a blank page in such cases.
The ConfirmDelete page now uses parts of the photopage. The
Confirmation dialog is its own template which is based on Alert.
The database now updates the album thumb to the most recent
addition to the album, when the album thumb asset is being deleted.
When there are no pictures left in the album 0 will be set.
