webadmin: migrating vm count in host's vm column

In vm count column under host main tab, show migrating vm count as well.

Bug-Url: https://bugzilla.redhat.com/970195
Change-Id: I1ad6796dec7986ea9394c54e46a08946adaf48ed
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>