Improved default logback config
Removed "item playback" functionality.

This was causing problems with the cascading data deletion
and was fun but not totally useful. We can do something similar
but more lightweight later if required.
Removed 'set public' for assessments/del settings

This never really went anywhere and I don't think we'll have
time to do anything useful with this for now.

The underyling entity fields have been kept as they're used to
mark the pre-loaded settings and demo assessments.
Fixed regressed link on "edit delivery" form