Remove py26 support
Remove py26 support

The code will not pass on py26 testing, but who cares about py26
anymore anyway.

Change-Id: I3009a01b392ade130f0802b3a995565d46c46b0f

openstack/python-openstacksdk,dtroyer/python-openstacksdk,jsmartin/shade,openstack/python-openstacksdk,openstack-infra/shade,jsmartin/shade,stackforge/python-openstacksdk,openstack-infra/shade,stackforge/python-openstacksdk,dtroyer/python-openstacksdk