[sortable] Added test for sortable when more than one SortableGroup is used (issue 873)
[sortable] FIX for issue #873. Relocations should be calculated
using all group properties, not only using changed one.
[sortable] Fix compatibility with PHP 5.3 in the test
Merge pull request #874 from Mordred/sortable-groups

[sortable] Added test for sortable with multi SortableGroup