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

[xenophonf]

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).

[abednarik]

Sorry to bother, but we can close this one :)

Thanks.

[xenophonf]

Thank you!