Fix warning when running `tox -e debug`
Fix warning when running `tox -e debug`

Console complains warning as below:
WARNING:test command found but not installed in testenv
  cmd: /usr/bin/oslo_debug_helper

Change-Id: I8cb26d39d7c2af7c7dc3883b5ebec304890a8f49

stackforge/senlin-dashboard,stackforge/senlin-dashboard,openstack/senlin-dashboard,openstack/senlin-dashboard,openstack/senlin-dashboard,openstack/senlin-dashboard,stackforge/senlin-dashboard