Author: Charles Fulton
MDL-31158 make grade recovery site-configurable
http://git.moodle.org/gw?p=moodle.git;a=commit;h=dbe93bc7c7adc2f805f8a4bb28befc4b32424cec
http://github.com/moodle/moodle/commit/dbe93bc7c7adc2f805f8a4bb28befc4b32424cec
+ 2.3 en [recovergradesdefault,core_grades]
+ 2.3 en [recovergradesdefault_help,core_grades]