Throw Hibernate exception if we can't cast to Enum
Properly pass already converted enums into nullSafeSet

We switched to putting them in a new array, but we were only loading the
new array when it wasn't already an integer. it'll already be an integer
when it's used via the criteria operators
Add enum domain classes / fields for testing
Add test for TestEnum creation
Add pgArrayContains test for EnumArrays
Add tests for pgArrayIsContainedBy with enum arrays
Add tests for pgArrayIsEmpty with enum arrays
Add test for pgArrayIsNotEmpty on enum arrays
Add tests for pgArrayOverlaps of enum arrays