Allow changes to the UUID after item deletion

[rakshasa]

• Add options to pass on delete to decide if the uuid should be preserved or not.
• Allow options to be passed on POST to change any old uuid.
• Allow PUT modify to change the uuid on deleted items.
• Add configuration option that decides what to do for:
  • Collision on POST.
  • Default on DELETE.

[rakshasa]

When an old UUID is being replaced it should probably be configurable/optional choice between adding a random post/prefix or generate a new random uuid.

[Metallion]

Done.