core,ui: allow disk live migration when VM is Paused

Allow live migrating a disk when the VM is in Paused status.
I.e. on each step of LSM process, verify that the VM
is in Up or Paused status.

Change-Id: I37926ba2ae87c334e6f2d17b65b91290fe2c3d39
Bug-Url: https://bugzilla.redhat.com/894035
Signed-off-by: Daniel Erez <derez@redhat.com>