Add localhost to the list of Horizon's ALLOWED_HOSTS
Add localhost to the list of Horizon's ALLOWED_HOSTS

Some monitoring scripts (such as openstack-utils) that live on the same
machine rely on Horizon being available on localhost in order to
function correctly.

Change-Id: Ia4716cca62a4009369ef3f25dd53ef998913511c

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