python3: Make iteritems py3k compat

Use six.iteritems to replace dictionary.iteritems() on python2 or
dictionary.items() on python3.

Change-Id: I972f065414e22d287bd7e00ab2c6e754f17afb75
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Merge "python3: Make iteritems py3k compat"