logica visivilidad de iconos profesor y alumno
filter by keyPatron = ':teacher' in view (teacher and student)
Description in English buttonName  plugin:Add External Pages to Course
parameter passing (is_course_plugin)
modificacion de codigo base Patron plugin para FUNCION DE ICONOS web IFRAME
implement install and uninstall of plugin AddExternalPagesPlugin : and reorder code
Merge pull request #76 from enlacee/8236

Fix the plugin icons to create new courses that did not correspond to these were shown, AND Fix  to create new courses EXTERNAL PAGES plugin not working - refs BT#8236