Consider drying up these two nearly identical functions

```javascript
function dateComparator(propName, field, dataObj, prefix) {
    return P.Form.validators.dateCompare(field, dataObj, prefix, function(val) {
        return val === null || val < moment(dataObj[propName]);
    });
}

...

daterangeUpper: dateComparator('lower'),
daterangeLower: dateComparator('upper'),

...