Deprecated iteritems() method not forward-compatible with Python 3

[aboe76]

the salt-formula uses iteritems in map.jinja

see:
https://github.com/saltstack-formulas/salt-formula/blob/master/salt/map.jinja#L5

Formulas iterating over dictionaries should use the items() method instead of iteritems() because the latter method has been removed from Python 3. While the items() method in Python 2 uses more memory than iteritems(), these dictionaries are typically small (e.g., sets of settings from Pillar).