Ignore AR base classes when validating uniqueness. Addresses #418.
Added test for #418.
Merge remote-tracking branch 'upstream/3-2-stable' into ignore-base-classes-when-validating-uniqueness
Merge branch '3-2-stable' of https://github.com/bcardarella/client_side_validations into ignore-base-classes-when-validating-uniqueness
Merge pull request #487 from joshweinstein/ignore-base-classes-when-validating-uniqueness

Ignore base classes when validating uniqueness