cinder_internal_tenant_* is not predictable

[Takashi Kajinami]

Currently the following two parameters define project/user for cinder's internal tenant .

- cinder_internal_tenant_project_id
- cinder_internal_tenant_user_id

However these parameters accept only id, and don't accept name. Because of this the appropriate values are not predictable and operators always need two phase deployment like;

1. Deploy OpenStack
2. Create an internal project and user
3. Update configuration so that cinder.conf points the project id and user id assigned by 2

It would be useful if we can pass "predictable" names instead of ids so that users can determine parmaeters before deploying OpenStack.