Now using a natural sort algorithm that is more consistent between JS
and PHP (although not perfect in some corner cases)
- added OC.Util.naturalSortComparator that uses the same algo that was
used for the user list
- changed user list and files list to use OC.Util.naturalSortComparator
- removed toLowerCase() and changed the comparator to use
String.localeCompare()
- added unit tests
- added OC_NaturalSort that is used by OCP\Util::naturalSortCompare()
