core : VMs do not appear in virtual machine tab if host is selected in side pane

Vms do not appear in 'virtual machine' main tab if host
is selected in webadmin side pane. screen shows empty
(0 item) despite there are large number of vms running
on the host.

Change-Id: I8ac91785cdb8982349c1cd0364b5673d2817f9f2
Bug-Url: https://bugzilla.redhat.com/1063782
Signed-off-by: Ravi Nori <rnori@redhat.com>