Author: David Mudrák
MDL-53240 filetypes: Introduce the filetypes_util helper class
http://git.moodle.org/gw?p=moodle.git;a=commit;h=6c4a5fdf88ac8ad88c4e86cf9b54d2b55bf2fd58
http://github.com/moodle/moodle/commit/6c4a5fdf88ac8ad88c4e86cf9b54d2b55bf2fd58
+ 3.4 en [any,core_mimetypes]