core: dont use getVmPayload query for updateVmVersionCommand

when calling getVmPayloadQuery from updateVmVersionCommand there is NPE
because the current-user is null, since this command is executed
internaly.

replaced the call to the query with a simple db query

Change-Id: I37472aff69087e23cf4206819c84c0e0f115fcc2
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1148379
Signed-off-by: Omer Frenkel <ofrenkel@redhat.com>