Python 3 incompatible issue: iteritems

dict.iteritems() was removed in Python 3. This patch
replace dict.iteritems() with six.iteritems() to support
both Python 2 and Python 3

Closes-Bug: #1403071

Change-Id: I5bcee5db2d7188633d45e6161e0c956449ad2197
Merge "Python 3 incompatible issue: iteritems"