Author: Matthew Noorenberghe
MDL-41634 - URL Download Repository doesn't warn when asked to download non-image files
http://git.moodle.org/gw?p=moodle.git;a=commit;h=4342b9320dcf2f8420234e91fd47da081de9db2d
http://github.com/moodle/moodle/commit/4342b9320dcf2f8420234e91fd47da081de9db2d
+ 2.5 en [validfiletype,repository_url]