Fix cells instance deletion

Instance delete and soft_delete are broken with cells when the API
doesn't know the cell of an instance.  A traceback occurs in all child
cells.  Also: soft_delete results in a 'hard' type being sent to
child cells vs 'soft'.

Fixes bug 1154333

Change-Id: I13ac839fa13a66caa100a3459bcc8e1183821ff1
Merge "Fix cells instance deletion"