With Python3, the iteritems() method has been removed from dictionarys.
This leaves us with two options:
1) replace with six.iteritems(dictionary)
2) replace with dictionary.items()
The OpenStack Python 3 coders have documented their preference,
and we should follow it. Their preference is dictionary.items()
Change-Id: I2e27819404ae071bd21bfe4555e50dc8df9c65aa
Partially-Implements: blueprint barbican-py3