Git commits in Moodle 2.3.1 by Adam Olley

commit a44c303d636badaedbcbd6999c0dae07d4c6c97f
Author: Adam Olley <adam.olley@netspot.com.au>
Date:   Tue, 28 Feb 2012 13:58:11 +0800
Tag:    v2.3.1

MDL-31802: Remove section summaries from navigation_cache