Notification of string changes

Author: David Mudrak
MDL-27053 Code maturity info added to admin notifications page
The patch introduces a new string to be displayed at admin notifications
page. The maturity level message for upgrade/install reworded as
requested in the tracker.

The patch also adds a new core call to purge all caches at the beginning
of the upgrade. This must be done before the upgrade starts so that the
strings are re-fetched from the updated source and not from the on-disk
cache.


http://git.moodle.org/gw?p=moodle.git;a=commit;h=a95682b2b3a2e42649d50a316847ef60c83b3974
http://github.com/moodle/moodle/commit/a95682b2b3a2e42649d50a316847ef60c83b3974

+ 2.1dev en [configgeoipfile,core_admin]
+ 2.1dev en [maturitycoreinfo,core_admin]
+ 2.1dev en [maturitycorewarning,core_admin]