Fix warning when running tox
Fix warning when running tox

When running tox it would print out a warning:

  WARNING:test command found but not installed in testenv
    cmd: /usr/bin/find
    env: /opt/stack/keystone/.tox/py27
  Maybe you forgot to specify a dependency? See also the whitelist_externals envconfig setting.

This is because we forgot to specify a dependency.

Change-Id: I4270c52213159cefa04a63979ee0bb2e1a2fa35f

openstack/keystone,himanshu-setia/keystone,openstack/keystone,rajalokan/keystone,cernops/keystone,himanshu-setia/keystone,openstack/keystone,rajalokan/keystone,klmitch/keystone,ilay09/keystone,klmitch/keystone,rajalokan/keystone,mahak/keystone,mahak/keystone,ilay09/keystone,ilay09/keystone,cernops/keystone,mahak/keystone