Use upper-constraints for all tox targets
Use upper-constraints for all tox targets

The issue has been resolved by infra [0], so we can use upper
constraints for all targets.

[0]
http://lists.openstack.org/pipermail/openstack-dev/2016-August/101474.html

Change-Id: I5c0378bdc6ddb4f8d0a328f3e61092be6cd579ac

NaohiroTamura/ironic,openstack/ironic,openstack/ironic,SauloAislan/ironic,SauloAislan/ironic,pshchelo/ironic,NaohiroTamura/ironic,pshchelo/ironic