python3: Add basic compatibility support
python3: Add basic compatibility support

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

Change-Id: I623009200f3a90985a2c0178673df7d54b36a686
Signed-off-by: Chuck Short <753a8074f04ffd62a8fff7516e3ae689be8e35ad@canonical.com>

varunarya10/keystonemiddleware