Author: Aaron Barnes
MDL-34899 blocks/html: Allow instances to specify additional CSS classes
http://git.moodle.org/gw?p=moodle.git;a=commit;h=14bcde673d35610dc2bb04486476f1f26e36eb05
http://github.com/moodle/moodle/commit/14bcde673d35610dc2bb04486476f1f26e36eb05
+ 2.4 en [configclasses,block_html]
+ 2.4 en [configclasses_help,block_html]