The devstack setup service can update /etc/issue, displaying the status
of the installation and the VM's management IP. With this change, after
the devstack service finsihed, the login prompt will look like this:
OpenStack VM - Installed by DevStack
Management IP: 10.219.3.108
Devstack run: SUCCEEDED
DevStackOSDomU login:
This helps people to log in to their system.
Change-Id: Idd6bbd5faf9ced5618cd3e95191bfc3b89473fa2
da481d0d0a