Fix aggregated unread submission count in Team stream.
Fix aggregated unread submission count in Team stream.

IanDCarroll/exercism.io,RaptorRCX/exercism.io,nathanbwright/exercism.io,treiff/exercism.io,IanDCarroll/exercism.io,jtigger/exercism.io,tejasbubane/exercism.io,mhelmetag/exercism.io,jtigger/exercism.io,jtigger/exercism.io,treiff/exercism.io,mhelmetag/exercism.io,jtigger/exercism.io,tejasbubane/exercism.io,tejasbubane/exercism.io,RaptorRCX/exercism.io,IanDCarroll/exercism.io,nathanbwright/exercism.io,IanDCarroll/exercism.io,RaptorRCX/exercism.io,RaptorRCX/exercism.io,treiff/exercism.io,mhelmetag/exercism.io,nathanbwright/exercism.io,tejasbubane/exercism.io,mhelmetag/exercism.io,treiff/exercism.io,nathanbwright/exercism.io