IntervalArray equality operators
It seems like IntervalArray doesn't implement equality operations correctly

```python
In [32]: iser = pd.Series(pd.IntervalIndex.from_breaks([1, 2, 3, 4]))

In [33]: iser.array == iser[0]
Out[33]: False
```

I would expect Out[33] to be

```python
np.array([True, False, False])
```

This bubbles up to Series[interval]

cc @jschendel 

