Improving error handling of uniquing predicate
Refatoring -uniquingPredicateForModel:
Improving NSManagedObject subclasses
Style fixes
Broaden return types of adapter methods
Set encounteredError independently of argument
Handle nil or empty uniquing property keys
Stricter handling of property keys for uniquing
Merge pull request #5 from robb/remind101-master

Wrapping up* #117