Re-enabled a test that had been "temporarily" disabled long ago.
Added blame tracking for invalid object creation statements
Factored out the IdentifiableType and ManagedType stuff from ErraiEntityType

This lays the foundation for supporting mapped supertypes (a requested feature) as well as
embeddable types (not yet requested, so we'll hold off on doing it)
Added support for basic store and fetch of entities that subclass other entities. (refs ERRAI-645)

Still need to test and implement:
 * polymorphic query results
 * abstract entities
 * mapped superclasses (might be same as abstract entities)
 * unmapped superclasses (ensure state inherited from these is not stored and restored)
Added support for polymorphic query results (refs ERRAI-645)
Added the ability to query on an entity class which subclasses another entity. (refs ERRAI-645)
Added test that spans 3 levels of entity type hierarchy, just to be sure.
Added sanity-check test against Hibernate to validate our behaviours around inheritance
Added the ability to fetch entities by supertypes rather than exact type matching
Now ensuring generated IDs don't overlap between types that share a common superclass
Merge branch 'jpa-inheritance'