Provide mechanism for users to control data locality when using DIST

Programmable affinity either through:

1) statically (e.g. annotating a certain field as the key for consistent hashing)

• in our case this cannot be based on the hashCode() as the affinity requirement and object identity are not directly related

2) dynamically (e.g. providing a overridable/annotatable consistentHashCode() function)

This would help to assign entities (in multiple Caches), which are needed together in the same nodes (to avoid remote lookups)