Fix bug in bucketSort so that a comparison function is now provided to the sort function

The [built-in JavaScript sort method](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) will
perform a lexicographical (aka alphabetical) order by converting the elements of the array to strings. This can yield unexpected results when sorting numbers.
A comparison function can be passed into the sort method to indicate how array elements should be compared.