Add support for linked records to provide a single value as the linking attribute, (when the foreign and local keys are the same name).
Add support for linked records to provide a single value as the linking attribute, (when the foreign and local keys are the same name).

Also included, __CLASS__ and __PRIMARYKEY__ lookups to assist with model linking.

nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus,nicholasryan/CorePlus