Use items() instead of iteritems().

Python 3 does not provide iteritems() anymore [1]. items() provides a view
and works in Python 2 as well.

[1] http://docs.python.org/3.1/whatsnew/3.0.html
Merge pull request #33 from ogasser/use_items_instead_of_iteritems

Use items() instead of iteritems().