Modify notifications_db router to work on postgres
Modify notifications_db router to work on postgres

lyw07/kolibri,lyw07/kolibri,mrpau/kolibri,indirectlylit/kolibri,learningequality/kolibri,lyw07/kolibri,mrpau/kolibri,learningequality/kolibri,mrpau/kolibri,lyw07/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,learningequality/kolibri,learningequality/kolibri,indirectlylit/kolibri,mrpau/kolibri