Author: Rajesh Taneja
MDL-33618 Messages: Added support to disable message provider
http://git.moodle.org/gw?p=moodle.git;a=commit;h=fd0f7ac5c21ad398d3dfeb11079536923f32f54b
http://github.com/moodle/moodle/commit/fd0f7ac5c21ad398d3dfeb11079536923f32f54b
+ 2.7 en [enabled,core_message]