Add an entry in Travis matrix w/ cext
Add an entry in Travis matrix w/ cext

DXCanas/kolibri,indirectlylit/kolibri,learningequality/kolibri,benjaoming/kolibri,lyw07/kolibri,indirectlylit/kolibri,learningequality/kolibri,benjaoming/kolibri,mrpau/kolibri,lyw07/kolibri,lyw07/kolibri,DXCanas/kolibri,DXCanas/kolibri,mrpau/kolibri,benjaoming/kolibri,mrpau/kolibri,learningequality/kolibri,indirectlylit/kolibri,learningequality/kolibri,benjaoming/kolibri,lyw07/kolibri,indirectlylit/kolibri,DXCanas/kolibri,mrpau/kolibri