Order delta before calculating the storage root

We need to order the delta before calculating the storage root, because
the order is important if the storage root is calculated using a storage
proof. The problem is arises when the delta is different than at the
time the storage root was recorded, because we may require a different
node that is not part of the proof and so, the storage root can not be
calculated. The problem is solved by always order the delta to use the
same order when calculating the storage root while recording the
stroage proof and when calculating the storage root using
the storage proof.

To prevent this bug in future again, a regression test is added.

Fixes: https://github.com/paritytech/cumulus/issues/146