Fix #1199 Allow user to not assign any Calculation to an AS
Fix #1199 Allow user to not assign any Calculation to an AS

rockfruit/bika.lims,labsanmartin/Bika-LIMS,veroc/Bika-LIMS,veroc/Bika-LIMS,DeBortoliWines/Bika-LIMS,DeBortoliWines/Bika-LIMS,labsanmartin/Bika-LIMS,anneline/Bika-LIMS,anneline/Bika-LIMS,veroc/Bika-LIMS,DeBortoliWines/Bika-LIMS,rockfruit/bika.lims,labsanmartin/Bika-LIMS,anneline/Bika-LIMS