Add display/query caching to COD schedule view

Let's cache the query and output of this view. Some options:

a) We could cache it for only 5 minutes, so that updates to the schedule are reflected sooner without an admin having to clear the cache
b) Set a permanent cache and use http://drupal.org/project/cache_actions to invalidate the cache
c) Invalidate the cache through some glue code in cod_session
d) Document clearing the cache