Update person_spec.rb

You can simplify this test a lot. Here is my thought process.

1. No need to manually raise an error, it's extra overhead
2. Asserting that the full array is checked means it will catch any extra validations other people add so they know to test them
3. Person.save being false is tested at the framework level. If you other (more granular) tests pass, this will pass by design
Merge pull request #1 from marcqualie/patch-1

Update person_spec.rb