xenapi: display IP and DevStack result on console

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
Setup user and endpoints for Savanna

* create savanna user with admin role for auth token checks
* create service data_processing
* create savanna endpoint
* use savanna user for auth token checks

It's needed for running tempest tests.

Change-Id: Iff26960746e36012c275f43c0de0dedcaebc8b0a
Merge "xenapi: display IP and DevStack result on console"
Merge "Setup user and endpoints for Savanna"
Merge branch 'master' of github.com:openstack-dev/devstack