Fix issue assigning items to a Playlist not setting the calculatedDuration correctly.
Fix issue assigning items to a Playlist not setting the calculatedDuration correctly.

PeterMis/xibo-cms,PeterMis/xibo-cms,alexharrington/xibo-cms,xibosignage/xibo-cms,xibosignage/xibo-cms,alexharrington/xibo-cms,alexharrington/xibo-cms,dasgarner/xibo-cms,dasgarner/xibo-cms,alexharrington/xibo-cms,dasgarner/xibo-cms,xibosignage/xibo-cms,dasgarner/xibo-cms,PeterMis/xibo-cms,PeterMis/xibo-cms,xibosignage/xibo-cms,dasgarner/xibo-cms,PeterMis/xibo-cms,dasgarner/xibo-cms,xibosignage/xibo-cms,xibosignage/xibo-cms,alexharrington/xibo-cms