Return an array with attached, detached and changed relationship IDs on sync
Modify tests to also test the new behaviour
Updated docblock as per bencorlett's & franzliedke's suggestions
Merge branch 'sync_return_changes_4.1' of https://github.com/arvidbjorkstrom/laravel-framework into arvidbjorkstrom-sync_return_changes_4.1
Working on formatting.
Merge branch 'arvidbjorkstrom-sync_return_changes_4.1' into 4.1