Specify keystone SQL revocation driver
Specify keystone SQL revocation driver

The default keystone configuration file included with most distributions
uses the deprecated 'keystone.contrib.revoke.backends.kvs' revocation
backend driver.  Use the keystone.contrib.revoke.backends.sql driver
instead.

Change-Id: I2c125fbd62346063f6cf2dd8ed71fcc85095f402
backport: juno
Closes-Bug: 1404969

AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,Akasurde/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,kairoaraujo/openstack-manuals,kairoaraujo/openstack-manuals