DATAGRAPH-368 Add test demonstrating the issue.
DATAGRAPH-368 Handle transient property on detached entity.

In DetachedEntityState.setValue(), check if the property
to save exists on the Neo4jPersistentEntity instance.
If the property is marked transient, the property won't exist
on the entity. In that case, forward the request to the delegate.
DATAGRAPH-393 Use supplied RestGraphDatabase as GraphDatabase in MappingInfrastructure