Description of revoke configuration options

Configuration option = Default value	Description
[revoke]
cache_time = 3600	(IntOpt) Time to cache the revocation list and the revocation events (in seconds). This has no effect unless global and token caching are enabled.
caching = True	(BoolOpt) Toggle for revocation event caching. This has no effect unless global caching is enabled.
driver = sql	(StrOpt) Entrypoint for an implementation of the backend for persisting revocation events in the keystone.revoke namespace.
expiration_buffer = 1800	(IntOpt) This value (calculated in seconds) is added to token expiration before a revocation event may be removed from the backend.