Negative numbers are allowed as expiration dates for setup-keys

[mlsmaycon]

Entering -1 or -10 as expiration days for a setup key is allowed and allows a user to submit an API request.

We should use the same check as for User > Access tokens, 1 to 365 days, so let's consolidate the check and reuse in both objects.

[mlsmaycon]

fixed in #252