core: fix upgrade from 3.3 to 3.4

The script 03_03_0950_change_policy_names.sql was added in change
http://gerrit.ovirt.org/#/c/18645/ , this upgrade script hasn't been
backported to the 3.3 branch, thus when upgrading from 3.3 to 3.4 it
won't be applied.

Change-Id: Ie6b14486d615adadca6e5013c2be575b471edca9
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: fix vm checks in LiveMigrateVmDisksCommand

Change-Id: I36dae8623c99fcb1f93b59eb7461bd06a1f429fe
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: change while loop to foreach

Change-Id: Id2d68bc5ae15226a5e1005d91f1218546990d225
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: MoveOrCopyDiskCommand - reduce query count

When loading the vms for a disk, the vm device information is already
loaded - therefore there's no need to filter it out and then reload it
for each vm, we can use the values that were loaded during the first
query execution.

Change-Id: Ic4b15114bc72dc07de917692b60703008008ae13
Signed-off-by: Liron Aravot <laravot@redhat.com>