fixes #6400 - show * next to required fields on forms
fixes #6226 - if only one option for required field on new host page (ex. installation media), then automatically select it
fixes #6401 - change include blank option to 'No environments' or 'No subnets', etc if there are no select options
              change include blank option to 'Select environment' or 'Select subnet' if required field and more than one option