Nullify building owners when owner is destroyed

Dependent destroy will destroy all of the owner’s buildings. Nullify
will set their owner_ids to nil.
Remove redundant test

You’re already testing this in your unit test
Refactor feature specs

You should also test for the flash messages that are being displayed on
the pages.

You also don’t want to redirect if your save fails. Redirecting to the
new path will cause your `@building` model to be reinitialized.

When you render instead, the view template will be displayed but you’ll
still have the same `@building` instance with the errors attached to
it. This means the errors will show up in the view.

You needed to add the code into your application layout to display the
flashes. Since you’re using Foundation, I added the code that also
applies the foundation styles to your flashes. Try them out! they even
have close buttons that cause them to fade out
Refactor unit tests
Refactor building validations

You should use an array instead of a regex for checking the states. It
makes it easier to read if you store it in a constant instead of
directly in the validation.

You also want to make sure that when you do use regular expression that
you anchor your exression. Your previous regex for the city was only
checking that there was at least one character that matched. This new
one will check that all of the characters match, from the beginning of
the string to the end.
Refactor owner model
Merge pull request #1 from HeroicEric/ek_feedback

Ek feedback; modifications to specs, regex...