Simplify plugin registry logic.
Simplify plugin registry logic.

indirectlylit/kolibri,learningequality/kolibri,mrpau/kolibri,learningequality/kolibri,mrpau/kolibri,mrpau/kolibri,learningequality/kolibri,indirectlylit/kolibri,learningequality/kolibri,mrpau/kolibri,indirectlylit/kolibri,indirectlylit/kolibri