Bug Fix - default room avatar for an empty room should not be your own face

Changes:
- If the room has only two members, use the avatar of the second member even if this member is invited.
- The plain solid circle (without initial) is used only for an "empty room" without display name (We name "empty room" a room in which the current user is the only active member).

Riot/Model/Search/FilesSearchCellData.m

@@ -1,5 +1,6 @@
 /*
  Copyright 2016 OpenMarket Ltd
+ Copyright 2017 Vector Creations Ltd
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -74,7 +75,7 @@
         MXRoom *room = [searchDataSource.mxSession roomWithRoomId:roomId];
         if (room)
         {
-            roomDisplayName = room.vectorDisplayname;
+            roomDisplayName = room.riotDisplayname;
             if (!roomDisplayName.length)
             {
                 roomDisplayName = NSLocalizedStringFromTable(@"room_displayname_no_title", @"Vector", nil);