We don't make the dependency clear between identity and resource/assignment LDAP

[Henry Nash]

If we are using LDAP for Resource/Assignment, our code requires that you are using it for Identity. We only hint at this in our code comments, for instance in https://review.openstack.org/#/c/144824/16/keystone/resource/backends/ldap.py where we say:

# This is the only deep dependency from resource back
# to identity. The assumption is that if you are using
# LDAP for resource, you are using it for identity as well.

We should make it clear that is a requirement. We should also make sure that this requirement is made clear in configuration.rst

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/151930

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/151930
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=74c50bde079b2f5d46c2c92c5a4632781154cd2e
Submitter: Jenkins
Branch: master

commit 74c50bde079b2f5d46c2c92c5a4632781154cd2e
Author: Henry Nash <email address hidden>
Date: Sun Feb 1 10:07:42 2015 +0000

    Make the LDAP dependency clear between identity, resource & assignment

    We currently hint at the fact that there is dependency on LDAP for
    identity if we are using it for resource and/or assignment, but we
    don't make it clear enough. This patch fixes this.

    Change-Id: Ic6cbffbcd390c48ee40dd97f70403c6981dc951e
    Closes-Bug: 1415169