message: Show the room avatar for invites
  This changes to the room avatar instead of the inviter's avatar.
diff: @@ -334,12 +334,12 @@ module.exports = React.createClass({
  break;
  }
  case MessageCase.Invite: {
  + const RoomAvatar = sdk.getComponent("views.avatars.RoomAvatar");
  + const avatar = <RoomAvatar room={this.props.room} />;
  +
  const inviteMember = this._getInviteMember();
  - let avatar;
  let inviterElement;
  if (inviteMember) {
  - const MemberAvatar = sdk.getComponent("views.avatars.MemberAvatar");
  - avatar = (<MemberAvatar member={inviteMember} />);
  inviterElement = <span>
  <span className="mx_RoomPreviewBar_inviter">
  {inviteMember.rawDisplayName}
  