core: NPE on UpdateVmVersion call to GetVmPayloadQuery

some changes in the session mgmt caused a NPE on the call to
GetVmPayloadQuery from UpdateVmVersionCommand.
The NPE caused because the session isn't automatically copied to the
query, so in this patch it is manually set in the query params.

Change-Id: If0a0a5cf79a6eb7967ed4ae4454a763773b23d65
Signed-off-by: Omer Frenkel <ofrenkel@redhat.com>