accounts.yaml not clearly documented to explain users should be in separate tenants

[Jesse Keating]

Some tests assume that every user is in a unique tenant/project, however at first glance the documentation doesn't stress this and so an unsuspecting operator could put multiple users in the same project. The documentation should be more clear.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/177274

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/177274
Committed: https://git.openstack.org/cgit/openstack/tempest/commit/?id=9329985d47cb8b20c3469c88cfa87b69e372490b
Submitter: Jenkins
Branch: master

commit 9329985d47cb8b20c3469c88cfa87b69e372490b
Author: Matthew Treinish <email address hidden>
Date: Fri Apr 24 09:58:18 2015 -0400

    Cleanup some details about the accounts files

    This commit cleans up some details in the accounts.yaml sample file
    and the tempest configuration guide to provide missing details about
    how to create and use an accounts file. Specifically it adds more
    detailed comments to the sample file about each section, and in the
    config guide it removes obsolete sections and adds some missing
    details.

    Change-Id: Ic11335fe1215ab0625ea2308ccc75d22a284c432
    Closes-Bug: #1447851