sakaiproject/Hilary — pull request #199 by simong (2012-10-18 13:52:34+00:00)
Title: Caching of User objects with redis

This PR introduces redis caching for User objects.
It will only check redis when calls are made to `getPrincipal` (note: *not* getPrincipal**s** )
When a user is retrieved from Cassandra it will be stored in Redis (asynchronously)
When a user gets updated the cached object will be removed (synchronously) once the Cassandra query returns.