Config attributes for OPENSTACK_KEYSTONE_BACKEND

Bumped version to 9.0.2 and added some more options to README.md

Closes-Bug: 1320274
Change-Id: I985ed5fc662cef82372bccb3cc7485e150cb9eb0
Fix to allow login urls to be configurable

Add attrs for login_url, logout_url, login_redirect_url and webroot
Fix the root default for webroot on redhat
No behavior changes for ubuntu or suse, but they now have flexibility.

Change-Id: I5db29c6768444dd742c0625b05285761da85be76
Closes-Bug: #1321390