If no entity name, print the type.
Handle new entity id format.

Entity ids can either be sent as a string, or a map with an "$eid"
entry. The Eris::Entity::extractEntityId method handled extraction this
for us.
Handle entity references in export and import.

Through the new format for knowing if a value is an entity reference
("$eid") we can now see what values we need to alter when exporting.
When importing later on we then need to wait with setting attributes
with entity references until all entities have been resolved.