Add support for oslo_debug_helper to tox.ini
Add support for oslo_debug_helper to tox.ini

More info in docs - http://docs.openstack.org/developer/oslotest/features.html#debugging-with-oslo-debug-helper

Change-Id: I3099bc09fc8c099f4f7ee708fa64c05d04a54ae7

ekasitk/sahara,egafford/sahara,zhujzhuo/Sahara,crobby/sahara,matips/iosr-2015,crobby/sahara,bigfootproject/sahara,bigfootproject/sahara,redhat-openstack/sahara,zhujzhuo/Sahara,redhat-openstack/sahara,zhangjunli177/sahara,bigfootproject/sahara,esikachev/sahara-backup,matips/iosr-2015,matips/iosr-2015,crobby/sahara,redhat-openstack/sahara,ekasitk/sahara,zhangjunli177/sahara,ekasitk/sahara,tellesnobrega/sahara,henaras/sahara,openstack/sahara,zhujzhuo/Sahara,openstack/sahara,egafford/sahara,henaras/sahara,esikachev/sahara-backup,esikachev/sahara-backup,tellesnobrega/sahara,henaras/sahara,zhangjunli177/sahara