Convert x.iteritems() to six.iteritems(x)

Convert x.iteritems() to six.iteritems(x) for
python 3.x compatibility.

Change-Id: I040c1b753012d45e8bf9f3c20c4a39ef143959b9
Closes-bug: #1282888
Merge "Convert x.iteritems() to six.iteritems(x)"