Remember sorting

A cookie is saved for 60 days to remember sorting when a user sorts the
backlog on something else than the default 'rank'.

fixes sonyxperiadev/BacklogTool#53
Bugfixes for sorting

Fix for editing items not possible when sorting on something else than
rank.

Also fixed a bug where sorting was possible after editing and saving an
item even though the list was sorted on something else than rank.

fixes sonyxperiadev/BacklogTool#53