Pass iscsi_ip_address to openstack::all

This commit adds a parameter to the allinone class to allow it to pass
iscsi_ip_address to the openstack::all class.  This allows AIO
deployments to expose an address other than 127.0.0.1 (the default
in openstack::all) which is important if you intend to use an AIO node
as the controller for a multi-node cloud.

Partial-Bug: #1236137

Note to reviewers: even with this patch, you won't be able to attach iscsi volumes to instances on an AIO node until the following upstream change is merged and cherry-picked to stable/grizzly:

https://review.openstack.org/#/c/50823/

However, this patch can still be merged without the upstream change (without the upstream change it will alter the default value of iscsi_ip_address in cinder.conf to point to something other than 127.0.0.1; with the upstream change it will additionally set the same value in nova.conf).