Python 3: Replace iter.next() with six.next(iter)
Python 3: Replace iter.next() with six.next(iter)

Use six.next() to be Python 3 compatible.

Change-Id: Ia16148a759d368872787d5896a7b1dc42ffcdfb5

pratikmallya/python-swiftclient,VyacheslavHashov/python-swiftclient,zackmdavis/python-swiftclient,ironsmile/python-swiftclient,jeseem/python-swiftclient,sohonetlabs/python-swiftclient,ironsmile/python-swiftclient,varunarya10/python-swiftclient,openstack/python-swiftclient,VyacheslavHashov/python-swiftclient,iostackproject/IO-Bandwidth-Differentiation-Client,varunarya10/python-swiftclient,openstack/python-swiftclient,zackmdavis/python-swiftclient,JioCloud/python-swiftclient,iostackproject/IO-Bandwidth-Differentiation-Client,krnflake/python-hubicclient,pratikmallya/python-swiftclient,jeseem/python-swiftclient,sohonetlabs/python-swiftclient,JioCloud/python-swiftclient