Git commits in Moodle 2.1.7 by Adam Olley

commit bded2e91a0a0dd3d6a97a296ca3e9f34f77ba946
Author: Adam Olley <adam.olley@netspot.com.au>
Date:   Tue, 28 Feb 2012 13:58:11 +0800
Tag:    v2.1.7

MDL-31802: Remove section summaries from navigation_cache