Author: David Mudrák
MDL-47883 admin: Fix missing string in the plugin validation
http://git.moodle.org/gw?p=moodle.git;a=commit;h=52184908fafd77eff3574e53105b504116d172ed
http://github.com/moodle/moodle/commit/52184908fafd77eff3574e53105b504116d172ed
+ 2.7 en [validationmsg_foundlangfile,tool_installaddon]