Fail if the actual array has items but the expected is empty

[taromero]

Not ready to merge yet, as this makes the circular object test to fail.

it('should fail if expected is filled but actual is empty', function () {
   expect({ anArray: ['1'] }).to.not.containSubset({ anArray: [] });
})

The above (new) test was failing, so I tried to fix it (assuming it's a bug).

This makes the circular object test to fail. Before trying to fix that I'd like to know if this logic is ok, and any comments you might have regarding the circular object test failing (maybe it can be written on a different way, or maybe this new logic I'm trying to add is just wrong).

[taromero]

Closing since the feature was not approved on #19.