CategoricalIndex.equals incorrectly considers category order when unordered
```python
>>> import pandas as pd
>>> pd.CategoricalIndex(['a', 'b'], categories=['a', 'b']).equals(
...     pd.CategoricalIndex(['a', 'b'], categories=['b', 'a']))
False
```

I fixed this for regular Categoricals in https://github.com/pandas-dev/pandas/pull/16339, but that didn't affect CategoricalIndex.equals. Do we want `.equals` to ignore order when `ordered=False` on both (I think we do)?

Discovered during my CategoricalDtype refactor, which does fix it so that order is ignored when `order=False`.