message: Drop transitionary code in mark-unread
diff: @@ -121,15 +121,12 @@ function getNotification(notification) {
  return item;
  }
  - // Already on L17. Only needed here to fix pre-existing unread notifications. Remove in 2018.
  - const clippedParticipants = participants.slice(0, 3);
  -
  - const usernames = clippedParticipants
  + const usernames = participants
  .map(participant => participant.username)
  .join(' and ')
  .replace(/ and (.+) and/, ', $1, and'); // 3 people only: A, B, and C
  - const avatars = clippedParticipants.map(participant =>
  + const avatars = participants.map(participant =>
  <a href={`/${participant.username}`} class="avatar">
  <img alt={`@${participant.username}`} height="20" src={participant.avatar} width="20"/>
  </a>
  