Validation against negative values
Validation against negative values

In Priority, display order and recurrence detail
fixes xibosignage/xibo#1294
fixes xibosignage/xibo#1295

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