Deleted places and parties

[f27wood]

At the moment we have no way of indicating when a place or party has been deleted, or deleting these from the list. To look in to as part of a future addition.

[Conal-Tuohy]

For some of the EMu-derived entities, deleting the entity produces a "tombstone" record which merely records that the entity is no longer available. This "tombstone" is propagated through the API, allowing e.g. Trove to perform the same deletion on their own database. But for the places and parties, a deletion in EMu does not produce a tombstone record, so the deleted objects are just silently deleted from the API on a weekly basis.