Author: Peter Burnett
MDL-65471 upgrade: framework to reduce maintenance mode
http://git.moodle.org/gw?p=moodle.git;a=commit;h=027c770eabb2620c5032cc8b8bf9b8f28d5eae40
http://github.com/moodle/moodle/commit/027c770eabb2620c5032cc8b8bf9b8f28d5eae40
+ 4.2 en [cliupgradecompletenomaintenanceupgrade,core_admin]
+ 4.2 en [cliupgrademaintenancenotrequired,core_admin]
+ 4.2 en [cliupgrademaintenancerequired,core_admin]
+ 4.2 en [cliupgradesetlock,core_admin]
+ 4.2 en [cliupgradeunsetlock,core_admin]