Update instance properties values in child cells to create instance.

When using nova cells, in child cell, instance properties dict received
from API cell is returned by database that contains instance['name']. We
need to pop this from dict before creating a instance entry in child cell.

The system metadata also need to be recreated in child cell because instance
properties dict is converted to primitive which makes instance['system_metadata']
a list of dicts.

Fix bug #1193552

Change-Id: I43a8b4c1673a831b0c87881004eb0a7e5b149d9e
Merge "Update instance properties values in child cells to create instance."