[Horizon] switch from fqdn option to allowed_hosts and server_aliases
[Horizon] switch from fqdn option to allowed_hosts and server_aliases

Change-Id: Id7141dddb5e4b3ed16347bcb3091bba6a8d52ce3

fr34k8/packstack,xbezdick/packstack,openstack/packstack,imcsk8/packstack,imcsk8/packstack,openstack/packstack,openstack/packstack,mahak/packstack,mahak/packstack,mahak/packstack,fr34k8/packstack,stackforge/packstack,palmer159/openstack-test,stackforge/packstack,xbezdick/packstack,xbezdick/packstack,imcsk8/packstack,fr34k8/packstack,stackforge/packstack,palmer159/openstack-test,palmer159/openstack-test