fix (travis): fix tests. return promise from mock asyncFetchLinks()
fix (travis): fix tests. return promise from mock asyncFetchLinks()

mozilla/activity-streams,JaredKerim-Mozilla/activity-stream,sarracini/activity-stream,rlr/activity-streams,sarracini/activity-stream,Mardak/activity-stream,JaredKerim-Mozilla/activity-stream,mozilla/activity-stream,AdamHillier/activity-stream,rlr/activity-streams,sarracini/activity-stream,AdamHillier/activity-stream,JaredKerim-Mozilla/activity-stream,sarracini/activity-stream,mozilla/activity-stream,rlr/activity-streams,Mardak/activity-stream,mozilla/activity-streams,rlr/activity-streams,Mardak/activity-stream,AdamHillier/activity-stream,JaredKerim-Mozilla/activity-stream,mozilla/activity-stream,mozilla/activity-stream,Mardak/activity-stream,AdamHillier/activity-stream