Author: Marina Glancy
MDL-25451 roles: check if user can assign foles in block
http://git.moodle.org/gw?p=moodle.git;a=commit;h=7a4ff165cb1c99edd084862969e30b1e1231bad1
http://github.com/moodle/moodle/commit/7a4ff165cb1c99edd084862969e30b1e1231bad1
+ 3.0 en [notabletoassignroleshere,core_role]