Author: Sam Hemelryk
NOBUG: Added missing backup message provider string
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0b4cede202fea023ed96f24d6f6808b4808ce593
http://github.com/moodle/moodle/commit/0b4cede202fea023ed96f24d6f6808b4808ce593
+ 2.0 en [messageprovider:backup,core]