Add scheduling filter that prevents migration to same host

Inhibit migration if destination hostname resolves
to source host. In that case, libvirt will abort
anyway, so this check just prevents libvirt error
from happening.

In addition, avoid migrations to a host which
resolves to localhost, which is rarely, if ever,
a good thing.

Change-Id: I42021452205f3dc070388a43de92c8fd5ed6dbf2
Bug-Url: https://bugzilla.redhat.com/1107650
Signed-off-by: Martin Sivák <msivak@redhat.com>