MDL-32638 fixed capability checks for instructauthors and instructreviewers
MDL-32638 fixed capability checks for instructauthors and instructreviewers

The workshop_pluginfile() can't be more restrictive than the code that
actually displays the text with the embedded images. To view both
instructions fields in view.php, the capability to view the workshop is
enough. So the same level of access control is applied here by
require_login() at the top of the function.

dilawar/moodle