function isSubSet (aTestArray, aRefArray) {
		function isOutsideSet(sTestValue) {
			return aRefArray.indexOf(sTestValue) < 0; // value is not part of the reference set
		}
		return aTestArray && aRefArray && !aTestArray.some(isOutsideSet);
	}
Utility function that checks if the content of an array
is a subset of the content of a second (reference) array