Create Zone expects dict while should be only a string ? #24

Hello guys.
I'm using your class and I found a strange behaviour in the create_zone (line 8 _Zones.py).
I see that I need to send a dict to the var "policy" even if in creating a zone should be enough to send a string the with a policy_id (like the update function).

is it a wanted behaviour ? I mean, it's not a problem sending a crafted dict containing only 1 policy id but maybe I'm missing something...

thanks