webadmin: adding Affinity Groups views

* affiniy groups subtabs under cluster and VM main tab
* affinity group popup dialog for new, edit and remove

For more information please refer
to: http://www.ovirt.org/Features/VM-Affinity

Change-Id: Ibe5d6f6efe2b13297b653e1622a26c7b2b44cba8
Bug-Url: https://bugzilla.redhat.com/1036638
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>