Author: Eloy Lafuente (stronk7)
MDL-29262 backup: new setting to control the ttl of backup logs
Add one new backup setting, moving from the general CFG->loglifetime,
to be able to delete backup logged information often.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=14e2704ad4c49675d1c5536827f9d50a4d50e71e
http://github.com/moodle/moodle/commit/14e2704ad4c49675d1c5536827f9d50a4d50e71e
+ 2.3 en [configloglifetime,core_backup]
+ 2.3 en [generalsettings,core_backup]
+ 2.3 en [loglifetime,core_backup]