EKManagedObjectMapper use NSNull for hasOne
EKManagedObjectMapper use NSNull for hasOne

When filling ManagedObject's hasOneMapping, the EKManagedObjectMapper
ignores NSNull and is therefore impossible to remove the referenced
object.

lucasmedeirosleite/EasyMapping,ChronicStim/EasyMapping,ChronicStim/EasyMapping,lucasmedeirosleite/EasyMapping,ChronicStim/EasyMapping