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=7bc4ca8b88006e91b3a48e17834e815238b8a1d4
http://github.com/moodle/moodle/commit/7bc4ca8b88006e91b3a48e17834e815238b8a1d4
+ 2.6 en [sessionhandlerconflict,cachestore_memcache]
+ 2.6 en [sessionhandlerconflict,cachestore_memcached]