Author: David Mudrák
MDL-49329 admin: If unable to install a plugin, display the reason
http://git.moodle.org/gw?p=moodle.git;a=commit;h=36977a6d08e61da8ce78cddf59d140affdd98abb
http://github.com/moodle/moodle/commit/36977a6d08e61da8ce78cddf59d140affdd98abb
+ 3.0 en [notwritable_help,core_plugin]
- 3.0 en [notwritable_link,core_plugin]