adding allowBlank for datepicker
adding allowBlank for datepicker

mgenev/how-to-sane,IanVS/how-to-sane,johan--/how-to-sane,IanVS/how-to-sane,johan--/how-to-sane,YunnuY/xrp-old,YunnuY/xrp-old,mgenev/how-to-sane