Make image_list.sh independent of host IP address
Make image_list.sh independent of host IP address

We do not need the HOST_IP to be detected in order to be able to list
our images. So just set that to some dummy value before sourcing
functions.

This will allow tools like disk-image-builder to work regardless of
whether get_default_host_ip succeeds or not.

Change-Id: I9c22d2066e34309e70e56076e3d17c5db6ecee06

Mahito/devstack,samgoon/devstack,bswartz/devstack,openstack-dev/devstack,nawawi/openstack,richliu/devstack,bigswitch/devstack,richliu/devstack,samgoon/devstack,noironetworks/devstack,avvocatodemarchis/devstack,bigswitch/devstack,noironetworks/devstack,openstack-dev/devstack,mssumanth/devstack,bswartz/devstack,group-policy/devstack,mssumanth/devstack,dtroyer/devstack,group-policy/devstack,nawawi/openstack,dirkmueller/devstack,avvocatodemarchis/devstack,dtroyer/devstack,dirkmueller/devstack,Mahito/devstack