no longer showing NaN and NaN as different

I believe that this makes more sense when showing a diff.

### Example
If you had `{ o: NaN }` and then want to see what changed later and compare it against `{ o: NaN }` it is counter intuitive to show that the `NaN` value changed because it actually didn't change.

### Changes
- adding test to reproduce issue
- switching out deep-equal with deep-is