ui: fixing display of host fqdn in addHost form

In this patch we create the initial vds name record with the hostgroup domain
url.
Hostname should be field automatically based on the picked hostgroup and the
name. When user change the name field the hostname should be updated
accordingly.

Change-Id: I74e17d69423e1c02028f596ecafb13a21ab3e3ca
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1165668
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>