TypeError issue with Subspaces.partition()

[milesabarr]

Just starting to learn and try to use active_subspaces, but I ran into an issue with Subspaces.partition() where the type of n was np.int64, and not an int, which gave me an error. I edited my code in subspaces.py, line 173 to be as follows:

if 'int' not in str(type(n)):

You might find this clunky, but it works. I figured you would want to know about this and change your code accordingly.

[mathematicalmichael]

addressed in #52