Git commits in Moodle 2.3.0 by Jonathan Champ

commit 0885166fcc8457ed6049b204671dedf9ca6cbcef
Author: Jonathan Champ <jonathan_champ@ncsu.edu>
Date:   Wed, 02 May 2012 22:23:07 +0800
Tag:    v2.3.0-beta

MDL-32689 Allow Blocks to decide whether they are collapsible.