Import Array and Hash tests, and make `== blank` match behaviour with AS

[burke]

When ActiveSupport isn't loaded, [] == blank is false, but when it is loaded, it (correctly?) matches the behaviour of [] == empty.

I think it's fair to say the intended behaviour is for == blank to match the behaviour of when AS is loaded, so let's just special-case this.

We also import a bunch of Array and Hash tests here.