dev/core/#/233 Add apis to retrieve information about the ultimate destination contac...

dev/core/#/233 Add apis to retrieve information about the ultimate destination contact and source contacts for merged contacts.

This 'data structure' is 'owned' by core & somewhat subject to future change so establishing a tested methodology for retrieving contact history in
core can support extensions such as
- extended reports - which exposes an address_history tab
- privacy extensions - which need to recover and potentially delete contacts that were merged
into the current contact