Clean up

Removing stuff left over from a bad copy/paste. This is similar the
clean up in 4a4cdb0.
Add tests for the Unique validator

If it weren't for coverage I probably would have forgotten to add these
tests. There was a note in 68d46ab saying they'd be added at a later
time. At the time of that revision there was no way for the tests to
utilize the database. Now that they can, these tests are being added to
cover the functionality of the `Unique` validator.