Fix for comparisons of categorical and an scalar not in categories

[jankatins]

Up to now, a comparison of categorical data and a scalar, which
is not in the categories would return False for all elements when
it should raise a TypeError, which it now does.

Also fix that != comparisons would return False for all elements
when the more logical choice would be True.

Fixes the raised issue in #9836 (comment)

[kay1793]

Still asking why equality doesn't raise when comparing with a non-existing category.

[shoyer]

@kay1793 This is consistent with what Python does for non-comparable types:

# python 3
In [1]: 'foo' == 123
Out[1]: False

In [2]: 'foo' > 123
TypeError: unorderable types: str() > int()

[kay1793]

thanks.

[jreback]

merged via 35b20d8

thank you!