Since `TENANT_NAME` is unique if we use keystone v2 api,
so `TENANT_ID` is not needed if `TENANT_NAME` is provided
to configure OpenStack provider.
And also to set `TENANT_ID` is annoying to develop, because
`TENANT_ID` is not static by each environment.
This patch remove dependency of `TENANT_ID` and simply use
`TENANT_NAME`.