Author: Sara Arjona
MDL-87280 subsection: Add task to remove existing descriptions
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0f1b23a54bee216d81a8cef20243966d29649c10
http://github.com/moodle/moodle/commit/0f1b23a54bee216d81a8cef20243966d29649c10
+ 5.2 en [removeexistingdescriptions,mod_subsection]