What is a DatabaseManagement?

[bbjubjub2494]

As a consequence of #151, we realise that the DatabaseManagement interface seems to lack a clear stated purpose. We need to explore what its purpose could be before we decide what to do with it. Note that this does not concern UniqueDatabaseManagement — incidentally that's another consequence of overloaded terms.

I'll start

DatabaseManagement is a collection of utility functions that sit around the database/data repositories. This suggests that we should rename it but otherwise keep it as is.