python3: Python3.x compatibility

Mechanical change for python3 compatibility

Signed-off-by: Chuck Short <chuck.short@canonical.com>

Change-Id: I43b99f5823101d517a0e55178fbe9ddf20934117
Reviewed-on: https://review.openstack.org/29622
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins