function _addLabelIntoCategory(label){
            if(_isNewCategory(label.category)){
                vars.categories.push(label.category);
                _addCategoryIntoEditFormSelect(label.categoryId, label.category);
            }

            _reloadLabelList();
        }
Add specified label into category.
append label name to typeahead source,
and render list which the label has added.

@param label
@private