Author: Sam Hemelryk
MDL-45724 cache: admin screen now shows store warnings
Implemented a means by which cache store instance can communicate
warnings due to things such as conflicting configurations etc.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=67a77fa36f4fce06050457f37658be0a678d5776
http://github.com/moodle/moodle/commit/67a77fa36f4fce06050457f37658be0a678d5776
+ 2.7 en [sessionhandlerconflict,cachestore_memcache]
+ 2.7 en [sessionhandlerconflict,cachestore_memcached]