Minor rename of Proof of Play first/last shown columns.
Minor rename of Proof of Play first/last shown columns.

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