Return value of delete-database

[jsmassa]

So far delete-database could return anything depending on the backend-implementation.

Do we want to leave it this way or ?

Options:

1. We leave it as is and do not worry at all about the return value.
2. We do it like Datomic and return true as the documentation says.
3. We return true when the database existed and something happened and false when the database didn't exist.

[whilo]

I opt for following Datomic and throwing an error in all other cases.