Author: Dan Marsden
MDL-28410 Choice - allow single answer choice to be created
http://git.moodle.org/gw?p=moodle.git;a=commit;h=aa20227e9fd102ac5ffdc6d16157bf2a3c3c4231
http://github.com/moodle/moodle/commit/aa20227e9fd102ac5ffdc6d16157bf2a3c3c4231
+ 2.2 en [atleastoneoption,mod_choice]
- 2.2 en [fillinatleastoneoption,mod_choice]