Public checkbox visible upon badge drop

Issue [#442](https://github.com/mozilla/openbadges/issues/442)

The public checkbox is now immediately visible when a badge is dropped in the empty group. It is included during creation and hidden just as the other controls in group view. The input checkbox is now made child of the label to avoid having to pair labels and checkboxes via their id since new groups have yet to be assigned a resource id.

In addition, the empty group had controls which were invisible but clickable. The empty group could be named or deleted since the controls were just given opacity: 0, particularly in CSS declarations for .isNew. This was resolved by using display: none instead.