general cleanup

* tweak recovery email messages
* update Django version (security update)
* update copyright years
* remove unused config settings
* update model diagram (and instructions)

Signed-off-by: David Seaward <david.seaward@puri.sm>
1 job for master in 37 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Deb
passed #34305
liberty
deb

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