Author: Sara Arjona
MDL-67795 contentbank: new external for deleting content
http://git.moodle.org/gw?p=moodle.git;a=commit;h=f627173ce355c00147656892c8937462f76cdfac
http://github.com/moodle/moodle/commit/f627173ce355c00147656892c8937462f76cdfac
+ 3.9 en [nopermissiontodelete,contentbank]