API: Allow equality comparisons of Series with a categorical dtype and object type are allowed (GH8938)

closes #8938 
change to this (or can make rhs ``[2,2,4]`` (or whatever), just cannot be a categorical with different categories

```
In [14]: cat == np.array(cat_base2)
Out[14]: 
0    False
1     True
2    False
dtype: bool
```