Notification of string changes

Author: Helen Foster
MDL-23771 empty string removed, thanks to Ralf Hilgenstock for report


http://git.moodle.org/gw?p=moodle.git;a=commit;h=73c64ba64503016180e57ca82c4319583a20a8f2
http://github.com/moodle/moodle/commit/73c64ba64503016180e57ca82c4319583a20a8f2

- 2.0 en [pluginname_help,repository_dropbox]